diff --git a/src/model/Declaration.js b/src/model/Declaration.js
new file mode 100644
index 0000000..8858301
--- /dev/null
+++ b/src/model/Declaration.js
@@ -0,0 +1,38 @@
+import Port from './Port';
+import { extractExpression, extractType } from '../parser/WDL/utils/utils';
+
+/**
+ * Class representing binding points of workflow steps.
+ */
+export default class Declaration extends Port {
+  /**
+   * Create a Declaration.
+   *
+   * @param {string} name - Declaration name
+   * @param {ast} declaration - Declaration ast tree node
+   * @param {Step} step - Parent step this Declaration belongs to.
+   */
+  constructor(name, declaration, step) {
+    if (!name) {
+      throw new Error('Declaration must have a name');
+    }
+    if (!declaration.expression || !declaration.type) {
+      throw new Error('Declaration could be created only using declaration object');
+    }
+    super(name, step, {});
+
+    delete this.desc;
+
+    /**
+     * Declaration expression extracted object.
+     * @type {string}
+     */
+    this.expression = extractExpression(declaration.expression);
+    /**
+     * Declaration type.
+     * @type {string}
+     */
+    this.type = extractType(declaration.type);
+  }
+
+}
diff --git a/src/model/Group.js b/src/model/Group.js
index 2b54392..d1b410a 100644
--- a/src/model/Group.js
+++ b/src/model/Group.js
@@ -34,6 +34,65 @@ class Group extends Step {
     super(name, new Action(name, config), config);
 
     this.type = type || 'default';
+    /**
+     * Dictionary of Group's own declarations.
+     * @type {Object.<string, Declaration>}
+     */
+    this.ownDeclarations = {};
+  }
+
+  /**
+   * Add a child step.
+   *
+   * @param {Declaration} declaration - Declaration to add.
+   * @returns {Declaration} Added declaration. May be used for easy declaration creation.
+   * @throws {Error} Generic exception if a declaration with the same name already exists.
+   * @example
+   * const declaration = parent.addDeclaration(new Declaration('declaration', ...));
+   */
+  addDeclaration(declaration) {
+    const root = this.workflow();
+    const existingInRoot = root && root.declarations[declaration.name];
+    const ownExisting = this.ownDeclarations[declaration.name];
+    if (!existingInRoot && !ownExisting) {
+      if (declaration.step !== null) {
+        declaration.step.removeDeclaration(declaration.name, root);
+      }
+
+      declaration.step = this;
+
+      if (root) {
+        root.declarations[declaration.name] = declaration;
+      }
+      this.ownDeclarations[declaration.name] = declaration;
+    } else if (existingInRoot !== declaration && ownExisting !== declaration) {
+      throw new Error(`Cannot add a declaration with the same name ${declaration.name}.`);
+    }
+    return declaration;
+  }
+
+  /**
+   * Remove a declaration.
+   *
+   * @param {string} name - Declaration to remove.
+   * @param {Workflow} root - Declaration's workflow
+   * @example
+   * parent.removeDeclaration('declaration');
+   */
+  removeDeclaration(name, root = null) {
+    const workflow = root || this.workflow();
+    const declarationInRoot = workflow && workflow.declarations[name];
+    const declaration = this.ownDeclarations[name];
+    if (declarationInRoot) {
+      declarationInRoot.step = null;
+      delete workflow.declarations[name];
+    }
+    if (declaration) {
+      declaration.step = null;
+      delete this.ownDeclarations[name];
+    }
+
+    return declaration;
   }
 }
 
diff --git a/src/model/Step.js b/src/model/Step.js
index a6e96d8..a03261b 100644
--- a/src/model/Step.js
+++ b/src/model/Step.js
@@ -95,9 +95,9 @@ export default class Step {
    * Create a workflow step. You should {@link Workflow#add add} it to a workflow or a compound step.
    *
    * @param {string} name - Step name. Must be unique in a parent step (e.g. {@link Workflow}).
-   * @param {Action=} [action={}] action - Action to execute during the step. If no action is specified it will
+   * @param {Action|{}} action - Action to execute during the step. If no action is specified it will
    * automatically be created based on the configuration. Multiple steps may share a single action.
-   * @param {object} [config={}] - Action configuration containing input bindings.
+   * @param {object} config - Action configuration containing input bindings.
    * It should include action description in case the action is missing.
    *
    */
diff --git a/src/model/Workflow.js b/src/model/Workflow.js
index 75059a1..d7f0803 100644
--- a/src/model/Workflow.js
+++ b/src/model/Workflow.js
@@ -35,6 +35,12 @@ class Workflow extends Group {
      * @type {Object.<string, Action>}
      */
     this.actions = {};
+    /**
+     * Dictionary of all declarations accessible within workflow.
+     * @type {Object.<string, Declaration>}
+     */
+    this.declarations = {};
+
     if (config.ast) {
       this.ast = config.ast;
     }
diff --git a/src/parser/WDL/entities/WDLWorkflow.js b/src/parser/WDL/entities/WDLWorkflow.js
index 3f503bf..02e9817 100644
--- a/src/parser/WDL/entities/WDLWorkflow.js
+++ b/src/parser/WDL/entities/WDLWorkflow.js
@@ -3,6 +3,8 @@ import _ from 'lodash';
 import Workflow from '../../../model/Workflow';
 import Step from '../../../model/Step';
 import Group from '../../../model/Group';
+import Declaration from '../../../model/Declaration';
+import Port from '../../../model/Port';
 import { extractExpression, extractType, extractMetaBlock, WDLParserError } from '../utils/utils';
 import * as Constants from '../constants';
 
@@ -46,19 +48,13 @@ export default class WDLWorkflow {
    * @param {list} bodyList - list of the current parsing wdl body node
    * @param {string} name - current body name
    * @param {Step} parent - parent step
-   * @param {list} opts - nodes that prohibited for current stage to parse (in lower case)
+   * @param {[list]} opts - nodes that prohibited for current stage to parse (in lower case)
    */
   parseBody(bodyList, name, parent, opts = []) {
     const parentStep = parent || this.workflowStep;
-    let declarationsPassed = false;
     bodyList.forEach((item) => {
       const lcName = item.name.toLowerCase();
       if (_.indexOf(opts, lcName) < 0) {
-        if (lcName !== 'declaration') {
-          declarationsPassed = true;
-        } else if (declarationsPassed) {
-          throw new WDLParserError('Declarations are allowed only before other things of current scope');
-        }
         this.parsingProcessors[lcName].call(this, item, parentStep);
       } else {
         throw new WDLParserError(`In ${name} body keys [${opts}] are not allowed`);
@@ -89,7 +85,8 @@ export default class WDLWorkflow {
 
     const collection = extractExpression(item.attributes.collection);
 
-    const port = WDLWorkflow.getPortForBinding(this.workflowStep, parent, collection);
+    // in scatter the item is always an identifier, so it'll always be one port returned from .getPortsForBinding()
+    const [port] = WDLWorkflow.getPortsForBinding(this.workflowStep, parent, collection);
 
     opts.i[itemName] = {};
     opts.i[itemName].type = 'ScatterItem';
@@ -190,8 +187,17 @@ export default class WDLWorkflow {
     const declaration = node.attributes.key.source_string;
     const expression = extractExpression(nodeValue);
 
+    if (!step.i[declaration] && step instanceof Workflow && step.ownDeclarations[declaration]) {
+      // remove declaration and add it as an input
+      const declarationObj = step.removeDeclaration(declaration);
+      const port = new Port(declaration, step, { type: declarationObj.type });
+      _.forEach(declarationObj.outputs, conn => conn.to.bind(port));
+      step.i[declaration] = port;
+    }
+
     if (step.i[declaration]) {
-      step.i[declaration].bind(WDLWorkflow.getPortForBinding(this.workflowStep, parentStep, expression));
+      const bindings = WDLWorkflow.getPortsForBinding(this.workflowStep, parentStep, expression);
+      _.forEach(bindings, binding => step.i[declaration].bind(binding));
     } else {
       throw new WDLParserError(`Undeclared variable trying to be assigned: call '${step.name}' --> '${declaration}'`);
     }
@@ -209,19 +215,21 @@ export default class WDLWorkflow {
     const name = decl.name.source_string;
     const type = extractType(decl.type);
 
-    const obj = {};
-    obj[name] = {
-      type,
-    };
+    if (decl.expression === null) { // declaration is an input type
+      const obj = {};
+      obj[name] = {
+        type,
+      };
+      parentStep.action.addPorts({
+        i: obj,
+      });
+    } else if (parentStep instanceof Group) { // declaration is a "variable" type
+      const declaration = new Declaration(name, decl, parentStep);
+      const bindings = WDLWorkflow.getPortsForBinding(this.workflowStep, declaration.step, declaration.expression);
+      _.forEach(bindings, binding => declaration.bind(binding));
 
-    const str = extractExpression(decl.expression).string;
-    if (str !== '') {
-      obj[name].default = str;
+      parentStep.addDeclaration(declaration);
     }
-
-    parentStep.action.addPorts({
-      i: obj,
-    });
   }
 
   /**
@@ -254,34 +262,17 @@ export default class WDLWorkflow {
         type,
       };
 
-      let wfOutLinksList = [];
       if (expression.type !== 'MemberAccess') {
         obj[name].default = expression.string;
-      } else {
-        expression.accesses.forEach((v) => { v.to = name; });
-        wfOutLinksList = expression.accesses;
       }
 
       this.workflowStep.action.addPorts({
         o: obj,
       });
 
-      wfOutLinksList.forEach((i) => {
-        const startStep = WDLWorkflow.findStepInStructureRecursively(this.workflowStep, i.lhs);
-
-        if (startStep) {
-          if (startStep.o[i.rhs]) {
-            this.workflowStep.o[i.to].bind(startStep.o[i.rhs]);
-          } else {
-            throw new WDLParserError(
-              `In '${this.workflowStep.name}' 
-              output block undeclared variable is referenced: '${i.lhs}.${i.rhs}'`);
-          }
-        } else {
-          throw new WDLParserError(
-            `In '${this.workflowStep.name}' 
-            output block undeclared call is referenced: '${i.lhs}'`);
-        }
+      const bindings = WDLWorkflow.getPortsForBinding(this.workflowStep, this.workflowStep, expression, true);
+      _.forEach(bindings, (binding) => {
+        this.workflowStep.o[name].bind(binding);
       });
     });
   }
@@ -309,15 +300,10 @@ export default class WDLWorkflow {
       });
       // WF output connections
       if (!wildcard) { // syntax: call_name.output_name
-        const callOutput = fqn.source_string.split('.');
-        if (callOutput.length < 2) {
-          return;
-        }
-        const callName = callOutput[0];
-        const outputName = callOutput[1];
+        const [callName, outputName] = fqn.source_string.split('.');
         const startStep = WDLWorkflow.findStepInStructureRecursively(this.workflowStep, callName);
 
-        if (startStep) {
+        if (startStep && startStep instanceof Step) {
           if (startStep.o[outputName]) {
             this.workflowStep.o[fqn.source_string].bind(startStep.o[outputName]);
           } else {
@@ -325,6 +311,8 @@ export default class WDLWorkflow {
               `In '${this.workflowStep.name}' 
               output block undeclared variable is referenced: '${callName}.${outputName}'`);
           }
+        } else if (startStep && startStep instanceof Port) {
+          this.workflowStep.o[fqn.source_string].bind(startStep);
         } else {
           throw new WDLParserError(
             `In '${this.workflowStep.name}' 
@@ -334,7 +322,7 @@ export default class WDLWorkflow {
         const callName = fqn.source_string;
         const startStep = WDLWorkflow.findStepInStructureRecursively(this.workflowStep, callName);
 
-        if (startStep) {
+        if (startStep && startStep instanceof Step) {
           if (_.size(startStep.o)) {
             _.forEach(startStep.o, (output, outputName) => {
               this.workflowStep.o[`${fqn.source_string}.*`].bind(startStep.o[outputName]);
@@ -344,6 +332,8 @@ export default class WDLWorkflow {
               `In '${this.workflowStep.name}' 
               output block undeclared variable is referenced: '${callName}.* (${callName} doesn't have any outputs)`);
           }
+        } else if (startStep && startStep instanceof Port) {
+          this.workflowStep.o[`${fqn.source_string}.*`].bind(startStep);
         } else {
           throw new WDLParserError(
             `In '${this.workflowStep.name}' 
@@ -355,20 +345,29 @@ export default class WDLWorkflow {
 
   static findStepInStructureRecursively(step, name) {
     let result = null;
-    _.forEach(step.children, (item, key) => {
-      if (key === name) {
-        result = item;
-        return false;
-      }
+    if (step.declarations && Object.keys(step.declarations).includes(name)) {
+      result = step.declarations[name];
+    }
+    if (!result && step instanceof Group && step.i && Object.keys(step.i).includes(name)) {
+      result = step.i[name];
+    }
 
-      result = WDLWorkflow.findStepInStructureRecursively(item, name);
+    if (!result) {
+      _.forEach(step.children, (item, key) => {
+        if (key === name) {
+          result = item;
+          return false;
+        }
 
-      if (result) {
-        return false;
-      }
+        result = WDLWorkflow.findStepInStructureRecursively(item, name);
 
-      return undefined;
-    });
+        if (result) {
+          return false;
+        }
+
+        return undefined;
+      });
+    }
 
     return result;
   }
@@ -378,6 +377,10 @@ export default class WDLWorkflow {
       if (_.has(step.i, portName) || _.has(step.o, portName)) {
         return step;
       }
+      const root = step.workflow();
+      if (_.has(root.declarations, portName)) {
+        return root;
+      }
 
       return WDLWorkflow.groupNameResolver(step.parent, portName);
     }
@@ -385,28 +388,76 @@ export default class WDLWorkflow {
     return undefined;
   }
 
-  static getPortForBinding(workflow, parent, expression) {
-    let binder = expression.string;
-    if (expression.type === 'MemberAccess') {
-      const rhsPart = expression.accesses[0].rhs;
-      const lhsPart = expression.accesses[0].lhs;
-
-      const outputStep = WDLWorkflow.findStepInStructureRecursively(workflow, lhsPart);
-      if (outputStep) {
-        if (outputStep.o[rhsPart]) {
-          binder = outputStep.o[rhsPart];
-        } else {
-          throw new WDLParserError(`Undeclared variable is referenced: '${lhsPart}.${rhsPart}'`);
+  static getPortsForBinding(workflow, parent, expression, isWfOutput = false) {
+    const accessesTypes = [
+      'ArrayOrMapLookup',
+      'MemberAccess',
+      'FunctionCall',
+      'ArrayLiteral',
+      'ObjectLiteral',
+      'MapLiteral',
+      'TupleLiteral',
+      'LogicalNot',
+      'UnaryPlus',
+      'UnaryNegation',
+      'Add',
+      'Subtract',
+      'Multiply',
+      'Divide',
+      'Remainder',
+      'LogicalOr',
+      'LogicalAnd',
+      'Equals',
+      'NotEquals',
+      'LessThan',
+      'LessThanOrEqual',
+      'GreaterThan',
+      'GreaterThanOrEqual',
+      'TernaryIf',
+      'MapLiteralKv',
+      'ObjectKV',
+    ];
+    const errorMessAdd = isWfOutput ? `in ${workflow.name} output block ` : '';
+    let binder = [expression.string];
+    if (accessesTypes.includes(expression.type) && expression.accesses.length) {
+      binder = [];
+      _.forEach(expression.accesses, (accesses) => {
+        if (_.isObject(accesses)) {
+          const outputStep = WDLWorkflow.findStepInStructureRecursively(workflow, accesses.lhs);
+          if (outputStep && outputStep instanceof Step) {
+            if (outputStep.o[accesses.rhs]) {
+              binder.push(outputStep.o[accesses.rhs]);
+            } else {
+              throw new WDLParserError(`Undeclared variable ${errorMessAdd}is referenced: '${accesses.lhs}.${accesses.rhs}'`);
+            }
+          } else if (outputStep && outputStep instanceof Port) {
+            binder.push(outputStep);
+          } else {
+            throw new WDLParserError(`Undeclared call ${errorMessAdd}is referenced: '${accesses.lhs}'`);
+          }
+        } else if (_.isString(accesses)) {
+          const desiredStep = WDLWorkflow.groupNameResolver(parent, accesses);
+          if (desiredStep) {
+            if (desiredStep.i[accesses]) {
+              binder.push(desiredStep.i[accesses]);
+            } else {
+              binder.push(desiredStep.declarations[accesses]);
+            }
+          } else {
+            throw new WDLParserError(`Undeclared variable ${errorMessAdd}is referenced: '${expression.string}'`);
+          }
         }
-      } else {
-        throw new WDLParserError(`Undeclared call is referenced: '${lhsPart}'`);
-      }
+      });
     } else if (expression.type === 'identifier') {
       const desiredStep = WDLWorkflow.groupNameResolver(parent, expression.string);
       if (desiredStep) {
-        binder = desiredStep.i[expression.string];
+        if (desiredStep.i[expression.string]) {
+          binder = [desiredStep.i[expression.string]];
+        } else {
+          binder = [desiredStep.declarations[expression.string]];
+        }
       } else {
-        throw new WDLParserError(`Undeclared variable is referenced: '${expression.string}'`);
+        throw new WDLParserError(`Undeclared variable ${errorMessAdd}is referenced: '${expression.string}'`);
       }
     }
 
diff --git a/src/parser/WDL/parse.js b/src/parser/WDL/parse.js
index 61a9211..d01df32 100644
--- a/src/parser/WDL/parse.js
+++ b/src/parser/WDL/parse.js
@@ -4,6 +4,7 @@ import Context from './entities/Context';
 import Parser from './hermes/wdl_parser';
 import * as Constants from './constants';
 import DataService from './../../dataServices/data-service';
+import { renameExpression, replaceSplitter } from './utils/renaming_utils';
 
 function hermesStage(data) {
   let tokens;
@@ -83,19 +84,6 @@ function getImports(ast) {
     }) : [];
 }
 
-function replaceDot(name) {
-  let res;
-  const splitted = name.split(Constants.NS_SPLITTER);
-  if (splitted.length > 2) {
-    const last = splitted.pop();
-    res = `${splitted.join(Constants.NS_CONNECTOR)}${Constants.NS_SPLITTER}${last}`;
-  } else {
-    res = splitted.join(Constants.NS_CONNECTOR);
-  }
-
-  return res;
-}
-
 function renameCallInput(callInput, prefix, initialCalls) {
   if (callInput.name.toLowerCase() === Constants.CALL_IO_MAPPING) {
     const valueType = callInput.attributes.value.name ? callInput.attributes.value.name.toLowerCase() : null;
@@ -103,7 +91,7 @@ function renameCallInput(callInput, prefix, initialCalls) {
       const calls = initialCalls.map(call => call.split(Constants.NS_SPLITTER).pop());
       const index = calls.indexOf(callInput.attributes.value.attributes.lhs.source_string);
       if (index > -1) {
-        callInput.attributes.value.attributes.lhs.source_string = `${prefix}${replaceDot(initialCalls[index])}`;
+        callInput.attributes.value.attributes.lhs.source_string = `${prefix}${replaceSplitter(initialCalls[index])}`;
       }
     }
   }
@@ -127,7 +115,7 @@ function renameWfOutput(output, prefix, initialCalls) {
         const calls = initialCalls.map(call => call.split(Constants.NS_SPLITTER).pop());
         const index = calls.indexOf(output.attributes.expression.attributes.lhs.source_string);
         if (index > -1) {
-          output.attributes.expression.attributes.lhs.source_string = `${prefix}${replaceDot(initialCalls[index])}`;
+          output.attributes.expression.attributes.lhs.source_string = `${prefix}${replaceSplitter(initialCalls[index])}`;
         }
       }
       break;
@@ -139,7 +127,7 @@ function renameWfOutput(output, prefix, initialCalls) {
 }
 
 function renameCallAst(call, prefix, initialCalls) {
-  if (!initialCalls.includes(call.attributes.task.source_string)) {
+  if (!initialCalls.includes(call.attributes.task.source_string) && !call.attributes.alias) {
     initialCalls.push(call.attributes.task.source_string);
   }
   if (call.attributes.body && call.attributes.body.attributes && call.attributes.body.attributes.io) {
@@ -147,7 +135,7 @@ function renameCallAst(call, prefix, initialCalls) {
       .map(callInput => renameCallInputs(callInput, prefix, initialCalls));
   }
 
-  call.attributes.task.source_string = `${prefix}${replaceDot(call.attributes.task.source_string)}`;
+  call.attributes.task.source_string = `${prefix}${replaceSplitter(call.attributes.task.source_string)}`;
 
   return call;
 }
@@ -155,6 +143,10 @@ function renameCallAst(call, prefix, initialCalls) {
 function renameWfDefinition(definition, prefix, initialCalls) {
   switch (definition.name.toLowerCase()) {
     case Constants.DECLARATION:
+      renameExpression(definition.attributes.name, prefix, initialCalls);
+      if (definition.attributes.expression) {
+        renameExpression(definition.attributes.expression, prefix, initialCalls);
+      }
       break;
     case Constants.CALL:
       definition = renameCallAst(definition, prefix, initialCalls);
@@ -173,11 +165,11 @@ function renameWfDefinition(definition, prefix, initialCalls) {
 }
 
 function renameWfAstNames(node, prefix) {
-  node.attributes.name.source_string = `${prefix}${replaceDot(node.attributes.name.source_string)}`;
+  node.attributes.name.source_string = `${prefix}${replaceSplitter(node.attributes.name.source_string)}`;
   const initialCalls = [];
   // declarations, calls, outputs
   node.attributes.body.list = node.attributes.body.list.map((definition) => {
-    if (definition.name.toLowerCase() === Constants.CALL) {
+    if (definition.name.toLowerCase() === Constants.CALL && !definition.attributes.alias) {
       initialCalls.push(definition.attributes.task.source_string);
     }
     return renameWfDefinition(definition, prefix, initialCalls);
@@ -187,7 +179,7 @@ function renameWfAstNames(node, prefix) {
 }
 
 function renameTaskAstNames(node, prefix) {
-  node.attributes.name.source_string = `${prefix}${replaceDot(node.attributes.name.source_string)}`;
+  node.attributes.name.source_string = `${prefix}${replaceSplitter(node.attributes.name.source_string)}`;
 
   return node;
 }
@@ -273,9 +265,9 @@ function getPreparedSubWDLs(opts) {
 function clearWfDefinition(definition) {
   switch (definition.name.toLowerCase()) {
     case Constants.DECLARATION:
-      break;
-    case Constants.CALL:
-      definition = false;
+      if (definition.attributes.expression) {
+        definition.attributes.expression = null;
+      }
       break;
     case Constants.WF_OUTPUTS:
       definition.attributes.outputs.list = definition.attributes.outputs.list
@@ -286,12 +278,9 @@ function clearWfDefinition(definition) {
           return output;
         });
       break;
+    case Constants.CALL:
     default:
-      definition.attributes.body.list = definition.attributes.body.list.map(def => clearWfDefinition(def))
-        .filter(i => !!i && !_.isArray(i));
-      if (!definition.attributes.body.list.length) {
-        definition = false;
-      }
+      definition = false;
       break;
   }
 
diff --git a/src/parser/WDL/utils/renaming_utils.js b/src/parser/WDL/utils/renaming_utils.js
new file mode 100644
index 0000000..2ebeba2
--- /dev/null
+++ b/src/parser/WDL/utils/renaming_utils.js
@@ -0,0 +1,135 @@
+import * as Constants from '../constants';
+
+/**
+ * Replaces {@link Constants}.{@link NS_SPLITTER} with {@link Constants}.{@link NS_CONNECTOR} in the name string
+ * @param {String} name - the name string to handle
+ * */
+export function replaceSplitter(name) {
+  let res;
+  const split = name.split(Constants.NS_SPLITTER);
+  if (split.length > 2) {
+    const last = split.pop();
+    res = `${split.join(Constants.NS_CONNECTOR)}${Constants.NS_SPLITTER}${last}`;
+  } else {
+    res = split.join(Constants.NS_CONNECTOR);
+  }
+
+  return res;
+}
+
+function putEnumeratedExpressions(list, localScope, callback) {
+  list.forEach(item => callback(item, localScope.prefix, localScope.initialCalls));
+}
+
+const processors = {
+  FunctionCall: (scope) => {
+    putEnumeratedExpressions(scope.attr.params.list, scope, scope.renameExpression);
+  },
+  MemberAccess: (scope) => {
+    scope.renameExpression(scope.attr.lhs, scope.prefix, scope.initialCalls);
+  },
+  Unary: (scope) => {
+    scope.renameExpression(scope.attr.expression, scope.prefix, scope.initialCalls);
+  },
+  Binary: (scope) => {
+    scope.renameExpression(scope.attr.lhs, scope.prefix, scope.initialCalls);
+    scope.renameExpression(scope.attr.rhs, scope.prefix, scope.initialCalls);
+  },
+  Ternary: (scope) => {
+    scope.renameExpression(scope.attr.cond, scope.prefix, scope.initialCalls);
+    scope.renameExpression(scope.attr.iftrue, scope.prefix, scope.initialCalls);
+    scope.renameExpression(scope.attr.iffalse, scope.prefix, scope.initialCalls);
+  },
+  Kv: (scope) => {
+    scope.renameExpression(scope.attr.value, scope.prefix, scope.initialCalls);
+  },
+  ArrayOrMapLookup: (scope) => {
+    scope.renameExpression(scope.attr.lhs, scope.prefix, scope.initialCalls);
+    scope.renameExpression(scope.attr.rhs, scope.prefix, scope.initialCalls);
+  },
+  ArrayLiteral: (scope) => {
+    putEnumeratedExpressions(scope.attr.values.list, scope, scope.renameExpression);
+  },
+  ObjectLiteral: (scope) => {
+    putEnumeratedExpressions(scope.attr.map.list, scope, scope.renameExpression);
+  },
+  MapLiteral: (scope) => {
+    putEnumeratedExpressions(scope.attr.map.list, scope, scope.renameExpression);
+  },
+  TupleLiteral: (scope) => {
+    putEnumeratedExpressions(scope.attr.values.list, scope, scope.renameExpression);
+  },
+  Identifier: (scope) => {
+    const calls = scope.initialCalls.map(call => call.split(Constants.NS_SPLITTER).pop());
+    const index = calls.indexOf(scope.ast.source_string);
+    if (index > -1) {
+      scope.ast.source_string = `${scope.prefix}${replaceSplitter(scope.initialCalls[index])}`;
+    }
+  },
+  default: () => {
+    // no need to rename these types of declarations
+  },
+};
+
+const processorRemap = {
+  ArrayOrMapLookup: 'ArrayOrMapLookup',
+  FunctionCall: 'FunctionCall',
+  MemberAccess: 'MemberAccess',
+  ArrayLiteral: 'ArrayLiteral',
+  ObjectLiteral: 'ObjectLiteral',
+  MapLiteral: 'MapLiteral',
+  TupleLiteral: 'TupleLiteral',
+  identifier: 'Identifier',
+
+  string: 'default',
+  boolean: 'default',
+  integer: 'default',
+  float: 'default',
+
+  LogicalNot: 'Unary',
+  UnaryPlus: 'Unary',
+  UnaryNegation: 'Unary',
+
+  Add: 'Binary',
+  Subtract: 'Binary',
+  Multiply: 'Binary',
+  Divide: 'Binary',
+  Remainder: 'Binary',
+  LogicalOr: 'Binary',
+  LogicalAnd: 'Binary',
+  Equals: 'Binary',
+  NotEquals: 'Binary',
+  LessThan: 'Binary',
+  LessThanOrEqual: 'Binary',
+  GreaterThan: 'Binary',
+  GreaterThanOrEqual: 'Binary',
+
+  TernaryIf: 'Ternary',
+
+  MapLiteralKv: 'Kv',
+  ObjectKV: 'Kv',
+};
+
+/**
+ * Changes declaration's names in entire ast expression subtree according to prefix and initialCalls parameters
+ * @param {ast} ast - Ast tree node to be expressed
+ * @param {String} prefix - name prefix
+ * @param {[String]} initialCalls - array of initial call's names that need to be renamed
+ */
+export function renameExpression(ast, prefix, initialCalls) {
+  if (!ast) {
+    return;
+  }
+
+  const attr = ast.attributes;
+
+  const scope = {
+    ast,
+    prefix,
+    initialCalls,
+    renameExpression,
+    attr,
+  };
+
+  processors[processorRemap[ast.name || ast.str]](scope);
+}
diff --git a/src/parser/WDL/utils/utils.js b/src/parser/WDL/utils/utils.js
index b6eddaf..2ee93ea 100644
--- a/src/parser/WDL/utils/utils.js
+++ b/src/parser/WDL/utils/utils.js
@@ -57,7 +57,7 @@ const unaryUnScoped = [
 function putEnumeratedExpressions(list, localRes, callback) {
   list.map(item => callback(item))
     .forEach((item, idx) => {
-      localRes.accesses.concat(item.accesses);
+      localRes.accesses = localRes.accesses.concat(item.accesses);
       localRes.string += idx === 0 ? item.string : `, ${item.string}`;
     });
 }
@@ -162,6 +162,12 @@ const processors = {
 
     scope.res.string += ')';
   },
+  Identifier: (scope) => {
+    scope.res.string = scope.ast.source_string;
+    scope.res.type = scope.ast.str;
+
+    scope.res.accesses = scope.res.accesses.concat(scope.ast.source_string);
+  },
   default: (scope) => {
     if (scope.ast.str === 'string') {
       scope.res.string = `"${JSON.stringify(scope.ast.source_string).slice(1, -1)}"`;
@@ -181,9 +187,9 @@ const processorRemap = {
   ObjectLiteral: 'ObjectLiteral',
   MapLiteral: 'MapLiteral',
   TupleLiteral: 'TupleLiteral',
+  identifier: 'Identifier',
 
   string: 'default',
-  identifier: 'default',
   boolean: 'default',
   integer: 'default',
   float: 'default',
@@ -242,7 +248,7 @@ export function extractExpression(ast) {
 
 /**
  * Build the string from entire ast type subtree
- * @param {ast} ast - Ast tree node to be expressed
+ * @param {ast} declarationNode - Ast tree node to be expressed
  */
 export function extractType(declarationNode) {
   if (declarationNode === undefined || declarationNode === null) {
diff --git a/src/pipeline.scss b/src/pipeline.scss
index 9bc4971..c1ca62e 100644
--- a/src/pipeline.scss
+++ b/src/pipeline.scss
@@ -62,6 +62,21 @@ $port-color-available: $lime-green;
   @include grabbing;
 }
 
+.joint-type-visualdeclaration {
+  .root {
+    fill: $step-color;
+    stroke: $step-color;
+  }
+
+  .label {
+    font-weight: 500;
+    font-family: "Source Sans Pro", sans-serif;
+    font-size: 16px;
+    text-decoration: none;
+    text-transform: none;
+  }
+}
+
 .joint-type-visualstep.selected {
   .body {
     stroke: $raspberry;
diff --git a/src/visual/VisualDeclaration.js b/src/visual/VisualDeclaration.js
new file mode 100644
index 0000000..1aa0d1e
--- /dev/null
+++ b/src/visual/VisualDeclaration.js
@@ -0,0 +1,52 @@
+import _ from 'lodash';
+import joint from 'jointjs';
+
+const cDefaultWidth = 12;
+const cMinHeight = 50;
+const cPixelPerSymbol = 10;
+
+export default class VisualDeclaration extends joint.shapes.pn.Transition {
+
+  constructor(opts = { declaration: null, x: 0, y: 0 }) {
+    super(_.defaultsDeep(opts, {
+      position: {
+        x: (opts.x - cDefaultWidth / 2) || 0,
+        y: (opts.y - cMinHeight / 2) || 0,
+      },
+      type: 'VisualDeclaration',
+      attrs: {
+        '.label': {
+          text: opts.declaration.name,
+        },
+      },
+    }));
+
+    this.step = opts.declaration.step;
+    this.declaration = opts.declaration;
+  }
+
+  // eslint-disable-next-line class-methods-use-this
+  isPortEnabled() {
+    return true;
+  }
+
+  _getLabel() {
+    return this.declaration.name;
+  }
+
+  /**
+   * Obtains bounding box os the element. Overrides Model method.
+   * @param opts options, see joint.shapes.devs.Model.getBBox
+   * @returns {*}
+   */
+  getBBox(opts) {
+    const bbox = super.getBBox(opts);
+    const declaration = this.declaration;
+    if (declaration) {
+      const boxWidth = Math.max((cPixelPerSymbol * declaration.name.length), cDefaultWidth);
+      bbox.x -= boxWidth / 2;
+      bbox.width = boxWidth;
+    }
+    return bbox;
+  }
+}
diff --git a/src/visual/VisualLink.js b/src/visual/VisualLink.js
index 710cf53..337c765 100644
--- a/src/visual/VisualLink.js
+++ b/src/visual/VisualLink.js
@@ -5,7 +5,7 @@ import joint from 'jointjs';
  * Class that represents graphical link
  * @private
  */
-export default class VisualLink extends joint.shapes.devs.Link {
+export default class VisualLink extends joint.shapes.pn.Link {
 
   constructor(opts, readOnly) {
     const defaultLinkaAttr = readOnly ?
diff --git a/src/visual/Visualizer.js b/src/visual/Visualizer.js
index 208962b..c17802a 100644
--- a/src/visual/Visualizer.js
+++ b/src/visual/Visualizer.js
@@ -2,11 +2,14 @@ import _ from 'lodash';
 import joint, { V } from 'jointjs';
 
 import Workflow from '../model/Workflow';
+import Declaration from '../model/Declaration';
+import Port from '../model/Port';
 import Paper from './Paper';
 import VisualLink from './VisualLink';
 import VisualStep from './VisualStep';
 import VisualGroup from './VisualGroup';
 import VisualWorkflow from './VisualWorkflow';
+import VisualDeclaration from './VisualDeclaration';
 
 import Zoom from './Zoom';
 
@@ -176,6 +179,7 @@ export default class Visualizer {
     this._selectionEnabled = true;
     this._graph = graph;
     this._children = {};
+    this._declarations = {};
     this._timer = null;
     this._step = null;
     this.clear();
@@ -259,6 +263,7 @@ export default class Visualizer {
     this._graph.off('add', null, this);
     this._graph.clear();
     this._children = {};
+    this._declarations = {};
     this._step = null;
     this.selection = [];
   }
@@ -332,21 +337,76 @@ export default class Visualizer {
     });
   }
 
-  _loopPorts(ports, source, cellsToAdd, isEnabled) {
-    const children = this._children;
-    const links = this._graph.getConnectedLinks(source);
-    _.forEach(ports, (port) => {
-      if (!isEnabled(port.name)) {
-        return;
-      }
-      _.forEach(port.outputs, (conn) => {
+  get _connectionProcessors() {
+    return {
+      declarationToDeclaration: (conn, visDeclaration, links, cellsToAdd) => {
+        const declarations = this._declarations;
+        const targetName = conn.to.name;
+        if (declarations[targetName] &&
+          _.find(links, link => link.conn === conn) === undefined &&
+          declarations[targetName].isPortEnabled(conn.to.step.hasInputPort(conn.to), conn.to.name)) {
+          const isReadOnly = this._readOnly || this._isChildSubWorkflow(visDeclaration.declaration.step) ||
+            this._isChildSubWorkflow(declarations[targetName].step);
+          cellsToAdd[cellsToAdd.length] = new VisualLink({
+            source: {
+              id: visDeclaration.id,
+            },
+            target: {
+              id: declarations[targetName].id,
+            },
+            conn,
+          }, isReadOnly);
+        }
+      },
+      declarationToPort: (conn, visDeclaration, links, cellsToAdd) => {
+        const children = this._children;
+        const targetName = generateChildName(conn.to.step);
+        if (children[targetName] &&
+          _.find(links, link => link.conn === conn) === undefined &&
+          children[targetName].isPortEnabled(conn.to.step.hasInputPort(conn.to), conn.to.name)) {
+          const isReadOnly = this._readOnly || this._isChildSubWorkflow(visDeclaration.declaration.step) ||
+            this._isChildSubWorkflow(children[targetName].step);
+          cellsToAdd[cellsToAdd.length] = new VisualLink({
+            source: {
+              id: visDeclaration.id,
+            },
+            target: {
+              id: children[targetName].id,
+              port: conn.to.name,
+            },
+            conn,
+          }, isReadOnly);
+        }
+      },
+      portToDeclaration: (conn, port, source, links, cellsToAdd) => {
+        const declarations = this._declarations;
+        const targetDeclarationName = conn.to.name;
+        if (declarations[targetDeclarationName] &&
+          _.find(links, link => link.conn === conn) === undefined &&
+          declarations[targetDeclarationName].isPortEnabled()) {
+          const isReadOnly = this._readOnly || this._isChildSubWorkflow(source.step) ||
+            this._isChildSubWorkflow(declarations[targetDeclarationName].declaration.step);
+          cellsToAdd[cellsToAdd.length] = new VisualLink({
+            source: {
+              id: source.id,
+              port: port.name,
+            },
+            target: {
+              id: declarations[targetDeclarationName].id,
+            },
+            conn,
+          }, isReadOnly);
+        }
+      },
+      portToPort: (conn, port, source, links, cellsToAdd) => {
+        const children = this._children;
         const targetName = generateChildName(conn.to.step);
         if (children[targetName] &&
           _.find(links, link => link.conn === conn) === undefined &&
           children[targetName].isPortEnabled(conn.to.step.hasInputPort(conn.to), conn.to.name)) {
           const isReadOnly = this._readOnly || this._isChildSubWorkflow(source.step) ||
             this._isChildSubWorkflow(children[targetName].step);
-          const link = new VisualLink({
+          cellsToAdd[cellsToAdd.length] = new VisualLink({
             source: {
               id: source.id,
               port: port.name,
@@ -357,7 +417,39 @@ export default class Visualizer {
             },
             conn,
           }, isReadOnly);
-          cellsToAdd[cellsToAdd.length] = link;
+        }
+      },
+    };
+  }
+
+  _loopPorts(ports, source, visDeclarations, cellsToAdd, isEnabled) {
+    const links = this._graph.getConnectedLinks(source);
+    _.forEach(ports, (port) => {
+      if (!isEnabled(port.name)) {
+        return;
+      }
+      _.forEach(port.outputs, (conn) => {
+        if (conn.to instanceof Declaration) {
+          this._connectionProcessors
+            .portToDeclaration(conn, port, source, links, cellsToAdd);
+        } else if (conn.to instanceof Port) {
+          this._connectionProcessors
+            .portToPort(conn, port, source, links, cellsToAdd);
+        }
+      });
+    });
+  }
+
+  _loopDeclarations(visDeclarations, cellsToAdd) {
+    _.forEach(visDeclarations, (visDeclaration) => {
+      const links = this._graph.getConnectedLinks(visDeclaration);
+      _.forEach(visDeclaration.declaration.outputs, (conn) => {
+        if (conn.to instanceof Declaration) {
+          this._connectionProcessors
+            .declarationToDeclaration(conn, visDeclaration, links, cellsToAdd);
+        } else if (conn.to instanceof Port) {
+          this._connectionProcessors
+            .declarationToPort(conn, visDeclaration, links, cellsToAdd);
         }
       });
     });
@@ -371,6 +463,8 @@ export default class Visualizer {
     // validate call <-> step correspondence
     const children = this._children;
 
+    const declarations = this._declarations;
+
     // handle the renames
     const pickBy = _.pickBy || _.pick; // be prepared for legacy lodash 3.10.1
     const renamed = pickBy(children, (vStep, name) => name !== generateChildName(vStep.step));
@@ -420,15 +514,28 @@ export default class Visualizer {
     const updateOrCreateVisualSteps = (innerStep, parent = null) => {
       const name = generateChildName(innerStep);
       let visChild = children[name];
-      const opts = this.zoom.fromWidgetToLocal({
-        x: this.paper.el.offsetWidth / 2,
-        y: this.paper.el.offsetHeight / 2,
-      });
-      opts.step = innerStep;
       if (!visChild) {
+        const opts = this.zoom.fromWidgetToLocal({
+          x: this.paper.el.offsetWidth / 2,
+          y: this.paper.el.offsetHeight / 2,
+        });
+        opts.step = innerStep;
         visChild = createVisual(opts);
         children[name] = visChild;
         cellsToAdd[cellsToAdd.length] = visChild;
+        if (_.size(opts.step.ownDeclarations)) {
+          _.forEach(opts.step.ownDeclarations, (declaration) => {
+            let visDeclaration = declarations[declaration.name];
+            if (!visDeclaration) {
+              visDeclaration = new VisualDeclaration({ declaration, x: opts.x, y: opts.y });
+              cellsToAdd[cellsToAdd.length] = visDeclaration;
+              declarations[declaration.name] = visDeclaration;
+              visChild.embed(visDeclaration);
+              visChild.fit();
+              visChild.update();
+            }
+          });
+        }
         if (parent) {
           parent.embed(visChild);
           parent.fit();
@@ -452,10 +559,12 @@ export default class Visualizer {
     updateOrCreateVisualSteps(step);
 
     _.forEach(children, (child) => {
-      this._loopPorts(child.step.o, child, cellsToAdd, portName => child.isPortEnabled(false, portName));
-      this._loopPorts(child.step.i, child, cellsToAdd, portName => child.isPortEnabled(true, portName));
+      this._loopPorts(child.step.o, child, declarations, cellsToAdd, portName => child.isPortEnabled(false, portName));
+      this._loopPorts(child.step.i, child, declarations, cellsToAdd, portName => child.isPortEnabled(true, portName));
     });
 
+    this._loopDeclarations(declarations, cellsToAdd);
+
     this._graph.addCells(cellsToAdd);
   }
 
diff --git a/test/model/DeclarationTest.js b/test/model/DeclarationTest.js
new file mode 100644
index 0000000..e759f2c
--- /dev/null
+++ b/test/model/DeclarationTest.js
@@ -0,0 +1,30 @@
+import { expect } from 'chai';
+
+import Declaration from '../../src/model/Declaration';
+
+
+describe('model/Declaration', () => {
+
+  describe('constructor', () => {
+
+    const declarationAst = {
+      type: { id: 41, str: 'type', source_string: 'Int', line: 2, col: 3 },
+      name: { id: 39, str: 'identifier', source_string: 'foo', line: 2, col: 9 },
+      expression: { id: 17, str: 'float', source_string: '9', line: 2, col: 15 },
+    };
+    const name = 'foo';
+
+    it('requires a name', () => {
+      expect(() => new Declaration('', declarationAst, null)).to.throw(Error);
+      expect(() => new Declaration(name, declarationAst, null)).to.not.throw(Error);
+      expect(new Declaration(name, declarationAst, null).name).to.equal(name);
+    });
+
+    it('requires a declaration ast object with expression and type', () => {
+      expect(() => new Declaration(name)).to.throws(Error);
+      expect(() => new Declaration(name, {})).to.throws(Error);
+      expect(() => new Declaration(name, { type: declarationAst.type })).to.throws(Error);
+      expect(() => new Declaration(name, { expression: declarationAst.expression })).to.throws(Error);
+    });
+  });
+});
diff --git a/test/model/GroupTest.js b/test/model/GroupTest.js
index 47bee06..9e08089 100644
--- a/test/model/GroupTest.js
+++ b/test/model/GroupTest.js
@@ -2,6 +2,8 @@ import { expect } from 'chai';
 
 import Group from '../../src/model/Group';
 import Action from '../../src/model/Action';
+import Workflow from '../../src/model/Workflow';
+import Declaration from '../../src/model/Declaration';
 
 describe('model/Group', () => {
 
@@ -44,4 +46,163 @@ describe('model/Group', () => {
       expect(() => new Group(name, type, new Action(name, config))).to.throw(Error);
     });
   });
+
+  describe('.addDeclaration()', () => {
+
+    const declarationAst = {
+      type: { id: 41, str: 'type', source_string: 'Int', line: 2, col: 3 },
+      name: { id: 39, str: 'identifier', source_string: 'bar', line: 2, col: 9 },
+      expression: { id: 17, str: 'float', source_string: '9', line: 2, col: 15 },
+    };
+
+    it('links a declaration', () => {
+      const group = new Group('group');
+      const declaration = new Declaration('declaration', declarationAst, null);
+      group.addDeclaration(declaration);
+
+      expect(declaration.step).to.equal(group);
+      expect(group.ownDeclarations).to.have.all.keys(['declaration']);
+      expect(group.ownDeclarations).to.have.property('declaration', declaration);
+    });
+
+    it('returns added declaration', () => {
+      const group = new Group('group');
+      const declaration = new Declaration('declaration', declarationAst, null);
+
+      expect(group.addDeclaration(declaration)).to.equal(declaration);
+    });
+
+    it('allows multiple declarations', () => {
+      const group = new Group('group');
+      const declaration = new Declaration('declaration', declarationAst, null);
+      const declarationAst2 = {
+        type: { id: 41, str: 'type', source_string: 'Int', line: 2, col: 3 },
+        name: { id: 39, str: 'identifier', source_string: 'baz', line: 2, col: 9 },
+        expression: { id: 17, str: 'float', source_string: '10', line: 2, col: 15 },
+      };
+      const declaration2 = new Declaration('declaration2', declarationAst2, null);
+      group.addDeclaration(declaration);
+      group.addDeclaration(declaration2);
+
+      expect(declaration.step).to.equal(group);
+      expect(declaration2.step).to.equal(group);
+      expect(group.ownDeclarations).to.have.all.keys(['declaration', 'declaration2']);
+      expect(group.ownDeclarations).to.have.property('declaration', declaration);
+      expect(group.ownDeclarations).to.have.property('declaration2', declaration2);
+    });
+
+    it('allows a single parent only', () => {
+      const momGroup = new Group('mom');
+      const dadGroup = new Group('dad');
+      const declaration = new Declaration('declaration', declarationAst, null);
+      momGroup.addDeclaration(declaration);
+      dadGroup.addDeclaration(declaration);
+
+      expect(declaration.step).to.equal(dadGroup);
+      expect(momGroup.ownDeclarations).to.be.empty;
+      expect(dadGroup.ownDeclarations).to.have.all.keys(['declaration']);
+    });
+
+    it('forbids equal declaration names', () => {
+      const group = new Group('group');
+      const declaration = group.addDeclaration(new Declaration('declaration', declarationAst, null));
+
+      expect(() => group.addDeclaration(new Declaration('declaration', declarationAst, null))).to.throw(Error);
+      expect(declaration.step).to.equal(group);
+      expect(group.ownDeclarations).to.have.all.keys(['declaration']);
+      expect(group.ownDeclarations).to.have.property('declaration', declaration);
+    });
+
+    it('allows adding twice', () => {
+      const group = new Group('group');
+      const declaration = group.addDeclaration(new Declaration('declaration', declarationAst, null));
+
+      expect(() => group.addDeclaration(declaration)).to.not.throw(Error);
+      expect(declaration.step).to.equal(group);
+      expect(group.ownDeclarations).to.have.all.keys(['declaration']);
+      expect(group.ownDeclarations).to.have.property('declaration', declaration);
+    });
+
+    it('adds a declaration to a parent workflow', () => {
+      const root = new Workflow('root');
+      const group = new Group('group');
+      root.add(group);
+      const declaration = group.addDeclaration(new Declaration('declaration', declarationAst, null));
+
+      expect(root.declarations).to.have.all.keys(['declaration']);
+      expect(root.declarations).to.have.property('declaration', declaration);
+      expect(group.ownDeclarations).to.have.all.keys(['declaration']);
+      expect(group.ownDeclarations).to.have.property('declaration', declaration);
+    });
+
+    it('adds declarations to a grandparent workflow (top-to-bottom)', () => {
+      const root = new Workflow('root');
+      const parentGroup = new Group('parentGroup');
+      root.add(parentGroup);
+      const sonGroup = new Group('sonGroup');
+      parentGroup.add(sonGroup);
+      const declaration = sonGroup.addDeclaration(new Declaration('declaration', declarationAst, null));
+
+      expect(root.declarations).to.have.all.keys(['declaration']);
+      expect(root.declarations).to.have.property('declaration', declaration);
+      expect(parentGroup.ownDeclarations).to.be.empty;
+      expect(parentGroup.ownDeclarations).not.to.have.property('declaration');
+      expect(sonGroup.ownDeclarations).to.have.all.keys(['declaration']);
+      expect(sonGroup.ownDeclarations).to.have.property('declaration', declaration);
+    });
+
+    it('adds declarations to a grandparent workflow (bottom-to-top)', () => {
+      const root = new Workflow('root');
+      const parentGroup = new Group('parentGroup');
+      const sonGroup = new Group('sonGroup');
+      parentGroup.add(sonGroup);
+      root.add(parentGroup);
+      const declaration = sonGroup.addDeclaration(new Declaration('declaration', declarationAst, null));
+
+      expect(root.declarations).to.have.all.keys(['declaration']);
+      expect(root.declarations).to.have.property('declaration', declaration);
+      expect(parentGroup.ownDeclarations).to.be.empty;
+      expect(parentGroup.ownDeclarations).not.to.have.property('declaration');
+      expect(sonGroup.ownDeclarations).to.have.all.keys(['declaration']);
+      expect(sonGroup.ownDeclarations).to.have.property('declaration', declaration);
+    });
+  });
+
+  describe('.removeDeclaration()', () => {
+
+    const declarationAst = {
+      type: { id: 41, str: 'type', source_string: 'Int', line: 2, col: 3 },
+      name: { id: 39, str: 'identifier', source_string: 'bar', line: 2, col: 9 },
+      expression: { id: 17, str: 'float', source_string: '9', line: 2, col: 15 },
+    };
+
+    it('unlinks a declaration', () => {
+      const group = new Group('group');
+      const declaration = new Declaration('declaration', declarationAst, null);
+      group.addDeclaration(declaration);
+      group.removeDeclaration('declaration');
+
+      expect(declaration.step).to.be.null;
+      expect(group.ownDeclarations).to.be.empty;
+    });
+
+    it('allows missing names', () => {
+      const group = new Group('group');
+
+      expect(() => group.removeDeclaration('declaration')).to.not.throw(Error);
+    });
+
+    it('removes a declaration from a workflow', () => {
+      const root = new Workflow('root');
+      const group = new Group('group');
+      const declaration = new Declaration('declaration', declarationAst, null);
+      root.add(group);
+      group.addDeclaration(declaration);
+      group.removeDeclaration('declaration');
+
+      expect(root.declarations).to.be.empty;
+      expect(group.ownDeclarations).to.be.empty;
+      expect(declaration.step).to.be.null;
+    });
+  });
 });
diff --git a/test/parser/WDL/entities/WDLWorkflowTest.js b/test/parser/WDL/entities/WDLWorkflowTest.js
index 36750d2..0161324 100644
--- a/test/parser/WDL/entities/WDLWorkflowTest.js
+++ b/test/parser/WDL/entities/WDLWorkflowTest.js
@@ -94,6 +94,1782 @@ describe('parser/WDL/entities/WDLWorkflow', () => {
       expect(workflow.workflowStep.action.i).to.have.all.keys(['a', 'b']);
     });
 
+    it('allows MemberAccess to access not only the call statements', () => {
+      const ast = {
+        name: { id: 39, str: 'identifier', source_string: 'ContEstMuTect', line: 10, col: 10 },
+        body: {
+          list: [{
+            name: 'Declaration',
+            attributes: {
+              type: {
+                name: 'Type',
+                attributes: {
+                  name: { id: 41, str: 'type', source_string: 'Array', line: 11, col: 3 },
+                  subtype: { list: [{ id: 41, str: 'type', source_string: 'String', line: 11, col: 9 }] },
+                },
+              },
+              name: { id: 39, str: 'identifier', source_string: 'bams', line: 11, col: 17 },
+              expression: null,
+            },
+          }, {
+            name: 'Declaration',
+            attributes: {
+              type: {
+                name: 'Type',
+                attributes: {
+                  name: { id: 41, str: 'type', source_string: 'Array', line: 12, col: 3 },
+                  subtype: { list: [{ id: 41, str: 'type', source_string: 'String', line: 12, col: 9 }] },
+                },
+              },
+              name: { id: 39, str: 'identifier', source_string: 'bais', line: 12, col: 17 },
+              expression: null,
+            },
+          }, {
+            name: 'Declaration',
+            attributes: {
+              type: { id: 41, str: 'type', source_string: 'File', line: 14, col: 3 },
+              name: { id: 39, str: 'identifier', source_string: 'inputMAFLite', line: 14, col: 8 },
+              expression: { id: 27, str: 'string', source_string: 'test', line: 14, col: 23 },
+            },
+          }, {
+            name: 'Declaration',
+            attributes: {
+              type: {
+                name: 'Type',
+                attributes: {
+                  name: { id: 41, str: 'type', source_string: 'Pair', line: 15, col: 3 },
+                  subtype: {
+                    list: [{
+                      id: 41,
+                      str: 'type',
+                      source_string: 'Int',
+                      line: 15,
+                      col: 8,
+                    }, { id: 41, str: 'type', source_string: 'String', line: 15, col: 13 }],
+                  },
+                },
+              },
+              name: { id: 39, str: 'identifier', source_string: 'test', line: 15, col: 21 },
+              expression: {
+                name: 'TupleLiteral',
+                attributes: {
+                  values: {
+                    list: [{
+                      id: 34,
+                      str: 'integer',
+                      source_string: '1',
+                      line: 15,
+                      col: 29,
+                    }, { id: 27, str: 'string', source_string: 'one', line: 15, col: 32 }],
+                  },
+                },
+              },
+            },
+          }, {
+            name: 'Declaration',
+            attributes: {
+              type: {
+                name: 'Type',
+                attributes: {
+                  name: { id: 41, str: 'type', source_string: 'Pair', line: 16, col: 3 },
+                  subtype: {
+                    list: [{
+                      id: 41,
+                      str: 'type',
+                      source_string: 'Int',
+                      line: 16,
+                      col: 8,
+                    }, { id: 41, str: 'type', source_string: 'String', line: 16, col: 13 }],
+                  },
+                },
+              },
+              name: { id: 39, str: 'identifier', source_string: 'testTwo', line: 16, col: 21 },
+              expression: {
+                name: 'TupleLiteral',
+                attributes: {
+                  values: {
+                    list: [{
+                      id: 34,
+                      str: 'integer',
+                      source_string: '2',
+                      line: 16,
+                      col: 32,
+                    }, { id: 27, str: 'string', source_string: 'two', line: 16, col: 35 }],
+                  },
+                },
+              },
+            },
+          }, {
+            name: 'Declaration',
+            attributes: {
+              type: {
+                name: 'Type',
+                attributes: {
+                  name: { id: 41, str: 'type', source_string: 'Array', line: 17, col: 3 },
+                  subtype: {
+                    list: [{
+                      name: 'Type',
+                      attributes: {
+                        name: { id: 41, str: 'type', source_string: 'Pair', line: 17, col: 9 },
+                        subtype: {
+                          list: [{
+                            id: 41,
+                            str: 'type',
+                            source_string: 'String',
+                            line: 17,
+                            col: 14,
+                          }, { id: 41, str: 'type', source_string: 'String', line: 17, col: 22 }],
+                        },
+                      },
+                    }],
+                  },
+                },
+              },
+              name: { id: 39, str: 'identifier', source_string: 'bams_and_bais', line: 17, col: 31 },
+              expression: {
+                name: 'FunctionCall',
+                attributes: {
+                  name: { id: 39, str: 'identifier', source_string: 'zip', line: 17, col: 47 },
+                  params: {
+                    list: [{
+                      id: 39,
+                      str: 'identifier',
+                      source_string: 'bams',
+                      line: 17,
+                      col: 51,
+                    }, { id: 39, str: 'identifier', source_string: 'bais', line: 17, col: 57 }],
+                  },
+                },
+              },
+            },
+          }, {
+            name: 'Scatter',
+            attributes: {
+              item: {
+                id: 39,
+                str: 'identifier',
+                source_string: 'bam_and_bai',
+                line: 18,
+                col: 12,
+              },
+              collection: { id: 39, str: 'identifier', source_string: 'bams_and_bais', line: 18, col: 27 },
+              body: {
+                list: [{
+                  name: 'Call',
+                  attributes: {
+                    task: { id: 40, str: 'fqn', source_string: 'testTask', line: 19, col: 10 },
+                    alias: null,
+                    body: {
+                      name: 'CallBody',
+                      attributes: {
+                        declarations: { list: [] },
+                        io: {
+                          list: [{
+                            name: 'Inputs',
+                            attributes: {
+                              map: {
+                                list: [{
+                                  name: 'IOMapping',
+                                  attributes: {
+                                    key: {
+                                      id: 39,
+                                      str: 'identifier',
+                                      source_string: 'bam',
+                                      line: 21,
+                                      col: 9,
+                                    },
+                                    value: {
+                                      name: 'MemberAccess',
+                                      attributes: {
+                                        lhs: {
+                                          id: 39,
+                                          str: 'identifier',
+                                          source_string: 'bam_and_bai',
+                                          line: 21,
+                                          col: 15,
+                                        },
+                                        rhs: {
+                                          id: 39,
+                                          str: 'identifier',
+                                          source_string: 'left',
+                                          line: 21,
+                                          col: 27,
+                                        },
+                                      },
+                                    },
+                                  },
+                                }, {
+                                  name: 'IOMapping',
+                                  attributes: {
+                                    key: {
+                                      id: 39,
+                                      str: 'identifier',
+                                      source_string: 'bai',
+                                      line: 22,
+                                      col: 9,
+                                    },
+                                    value: {
+                                      name: 'MemberAccess',
+                                      attributes: {
+                                        lhs: {
+                                          id: 39,
+                                          str: 'identifier',
+                                          source_string: 'bam_and_bai',
+                                          line: 22,
+                                          col: 15,
+                                        },
+                                        rhs: {
+                                          id: 39,
+                                          str: 'identifier',
+                                          source_string: 'right',
+                                          line: 22,
+                                          col: 27,
+                                        },
+                                      },
+                                    },
+                                  },
+                                }],
+                              },
+                            },
+                          }],
+                        },
+                      },
+                    },
+                  },
+                }],
+              },
+            },
+          }, {
+            name: 'WorkflowOutputs',
+            attributes: {
+              outputs: {
+                list: [{
+                  name: 'WorkflowOutputWildcard',
+                  attributes: {
+                    fqn: { id: 40, str: 'fqn', source_string: 'inputMAFLite', line: 28, col: 5 },
+                    wildcard: null,
+                  },
+                }, {
+                  name: 'WorkflowOutputWildcard',
+                  attributes: {
+                    fqn: { id: 40, str: 'fqn', source_string: 'test', line: 29, col: 5 },
+                    wildcard: { id: 10, str: 'asterisk', source_string: '*', line: 29, col: 10 },
+                  },
+                }, {
+                  name: 'WorkflowOutputWildcard',
+                  attributes: {
+                    fqn: {
+                      id: 40,
+                      str: 'fqn',
+                      source_string: 'testTwo.right',
+                      line: 30,
+                      col: 5,
+                    },
+                    wildcard: null,
+                  },
+                }],
+              },
+            },
+          }],
+        },
+      };
+      const context = {
+        genericTaskCommandMap: [],
+        actionMap: {
+          testTask: {
+            _handlers: {},
+            name: 'testTask',
+            canHavePorts: true,
+            i: { bam: { type: 'File', multi: false }, bai: { type: 'File', multi: false } },
+            o: { out: { type: 'String', default: 'output', multi: false } },
+            data: {},
+          },
+          ContEstMuTect: {
+            name: 'ContEstMuTect',
+            action: {
+              _handlers: { changed: [[null, null]], 'port-rename': [[null, null]] },
+              name: 'ContEstMuTect',
+              canHavePorts: true,
+              i: {},
+              o: {},
+              data: {},
+            },
+            parent: null,
+            children: {},
+            i: {
+              bams: { type: 'Array[String]' },
+              bais: { type: 'Array[String]' },
+              inputMAFLite: { type: 'File', default: 'test' },
+              test: { type: 'Pair[Int, String]', default: '(1, "one")' },
+              testTwo: { type: 'Pair[Int, String]', default: '(2, "two")' },
+              bams_and_bais: { type: 'Array[Pair[String, String]]', default: 'zip(bams, bais)' },
+            },
+            o: {
+              inputMAFLite: { type: '', multi: false, default: 'inputMAFLite' },
+              'test.*': { type: '', multi: true, default: 'test.*' },
+              'testTwo.right': { type: '', multi: false, default: 'testTwo.right' },
+            },
+            type: 'workflow',
+            ownDeclarations: {},
+            actions: {
+              ContEstMuTect: {
+                _handlers: { changed: [[null, null]], 'port-rename': [[null, null]] },
+                name: 'ContEstMuTect',
+                canHavePorts: true,
+                i: {},
+                o: {},
+                data: {},
+              },
+            },
+            declarations: {},
+            isSubWorkflow: false,
+          },
+        },
+      };
+
+      const workflow = new WDLWorkflow(ast, context);
+
+      expect(workflow.workflowStep.o).to.have.all.keys(['inputMAFLite', 'test.*', 'testTwo.right']);
+    });
+
+
+    it('allows to override subWorkflow\'s declarations in call\'s inputs', () => {
+      const ast = {
+        name: { id: 39, str: 'identifier', source_string: 'wf1', line: 1, col: 10 },
+        body: {
+          list: [{
+            name: 'Declaration',
+            attributes: {
+              type: { id: 41, str: 'type', source_string: 'String', line: 2, col: 3 },
+              name: { id: 39, str: 'identifier', source_string: 'test', line: 2, col: 10 },
+              expression: { id: 27, str: 'string', source_string: 'test', line: 2, col: 17 },
+            },
+          }, {
+            name: 'Call',
+            attributes: {
+              task: { id: 40, str: 'fqn', source_string: 'wf2', line: 4, col: 8 },
+              alias: null,
+              body: {
+                name: 'CallBody',
+                attributes: {
+                  declarations: { list: [] },
+                  io: {
+                    list: [{
+                      name: 'Inputs',
+                      attributes: {
+                        map: {
+                          list: [{
+                            name: 'IOMapping',
+                            attributes: {
+                              key: {
+                                id: 39,
+                                str: 'identifier',
+                                source_string: 'test',
+                                line: 6,
+                                col: 7,
+                              },
+                              value: { id: 39, str: 'identifier', source_string: 'test', line: 6, col: 14 },
+                            },
+                          }],
+                        },
+                      },
+                    }],
+                  },
+                },
+              },
+            },
+          }],
+        },
+      };
+      const context = {
+        genericTaskCommandMap: [],
+        actionMap: {
+          wf1: {
+            name: 'wf1',
+            action: {
+              _handlers: { changed: [[null, null]], 'port-rename': [[null, null]] },
+              name: 'wf1',
+              canHavePorts: true,
+              i: {},
+              o: {},
+              data: {},
+            },
+            parent: null,
+            children: {},
+            i: { test: { type: 'String', default: 'test' } },
+            o: {},
+            type: 'workflow',
+            ownDeclarations: {},
+            actions: {
+              wf1: {
+                _handlers: { changed: [[null, null]], 'port-rename': [[null, null]] },
+                name: 'wf1',
+                canHavePorts: true,
+                i: {},
+                o: {},
+                data: {},
+              },
+            },
+            declarations: {},
+            isSubWorkflow: false,
+          },
+          wf2: {
+            name: 'wf2',
+            action: {
+              _handlers: { changed: [[null, null]], 'port-rename': [[null, null]] },
+              name: 'wf2',
+              canHavePorts: true,
+              i: {},
+              o: {},
+              data: {},
+            },
+            parent: null,
+            children: {},
+            i: { test: { type: 'String', default: 'test2' } },
+            o: {},
+            type: 'workflow',
+            ownDeclarations: {},
+            actions: {
+              wf2: {
+                _handlers: { changed: [[null, null]], 'port-rename': [[null, null]] },
+                name: 'wf2',
+                canHavePorts: true,
+                i: {},
+                o: {},
+                data: {},
+              },
+            },
+            declarations: {},
+            ast: {
+              name: 'Workflow',
+              attributes: {
+                name: { id: 39, str: 'identifier', source_string: 'wf2', line: 10, col: 10 },
+                body: {
+                  list: [{
+                    name: 'Declaration',
+                    attributes: {
+                      type: { id: 41, str: 'type', source_string: 'String', line: 11, col: 3 },
+                      name: { id: 39, str: 'identifier', source_string: 'test', line: 11, col: 10 },
+                      expression: { id: 27, str: 'string', source_string: 'test2', line: 11, col: 17 },
+                    },
+                  }],
+                },
+              },
+            },
+            isSubWorkflow: false,
+          },
+        },
+      };
+
+      const workflow = new WDLWorkflow(ast, context);
+
+      expect(workflow.workflowStep.children.wf2.i).to.have.all.keys(['test']);
+      expect(workflow.workflowStep.children.wf2.ownDeclarations).to.be.empty;
+    });
+
+    it('resolves connections for call inputs with declaration with multiple inputs', () => {
+      const ast = {
+        name: {
+          id: 39,
+          str: 'identifier',
+          source_string: 'foo',
+          line: 1,
+          col: 10,
+        },
+        body: {
+          list: [{
+            name: 'Declaration',
+            attributes: {
+              type: { id: 41, str: 'type', source_string: 'String', line: 2, col: 3 },
+              name: { id: 39, str: 'identifier', source_string: 'bar', line: 2, col: 10 },
+              expression: { id: 27, str: 'string', source_string: 'bar', line: 2, col: 16 },
+            },
+          }, {
+            name: 'Declaration',
+            attributes: {
+              type: { id: 41, str: 'type', source_string: 'String', line: 3, col: 3 },
+              name: { id: 39, str: 'identifier', source_string: 'baz', line: 3, col: 10 },
+              expression: { id: 27, str: 'string', source_string: 'baz', line: 3, col: 16 },
+            },
+          }, {
+            name: 'Call',
+            attributes: {
+              task: { id: 40, str: 'fqn', source_string: 'task1', line: 5, col: 8 },
+              alias: null,
+              body: {
+                name: 'CallBody',
+                attributes: {
+                  declarations: { list: [] },
+                  io: {
+                    list: [{
+                      name: 'Inputs',
+                      attributes: {
+                        map: {
+                          list: [{
+                            name: 'IOMapping',
+                            attributes: {
+                              key: {
+                                id: 39,
+                                str: 'identifier',
+                                source_string: 'in',
+                                line: 7,
+                                col: 7,
+                              },
+                              value: {
+                                name: 'FunctionCall',
+                                attributes: {
+                                  name: {
+                                    id: 39,
+                                    str: 'identifier',
+                                    source_string: 'select_first',
+                                    line: 7,
+                                    col: 12,
+                                  },
+                                  params: {
+                                    list: [{
+                                      name: 'ArrayLiteral',
+                                      attributes: {
+                                        values: {
+                                          list: [{
+                                            id: 39,
+                                            str: 'identifier',
+                                            source_string: 'bar',
+                                            line: 7,
+                                            col: 26,
+                                          }, {
+                                            id: 39,
+                                            str: 'identifier',
+                                            source_string: 'baz',
+                                            line: 7,
+                                            col: 31,
+                                          }],
+                                        },
+                                      },
+                                    }],
+                                  },
+                                },
+                              },
+                            },
+                          }],
+                        },
+                      },
+                    }],
+                  },
+                },
+              },
+            },
+          }],
+        },
+      };
+      const context = {
+        genericTaskCommandMap: [],
+        actionMap: {
+          task1: {
+            _handlers: {},
+            name: 'task1',
+            canHavePorts: true,
+            i: { in: { type: 'String', multi: false } },
+            o: {},
+            data: {},
+          },
+          foo: {
+            name: 'foo',
+            action: {
+              _handlers: { changed: [[null, null]], 'port-rename': [[null, null]] },
+              name: 'foo',
+              canHavePorts: true,
+              i: {},
+              o: {},
+              data: {},
+            },
+            parent: null,
+            children: {},
+            i: { bar: { type: 'String', default: 'bar' }, baz: { type: 'String', default: 'baz' } },
+            o: {},
+            type: 'workflow',
+            ownDeclarations: {},
+            actions: {
+              foo: {
+                _handlers: { changed: [[null, null]], 'port-rename': [[null, null]] },
+                name: 'foo',
+                canHavePorts: true,
+                i: {},
+                o: {},
+                data: {},
+              },
+            },
+            declarations: {},
+            ast: {
+              name: 'Workflow',
+              attributes: {
+                name: { id: 39, str: 'identifier', source_string: 'foo', line: 1, col: 10 },
+                body: {
+                  list: [{
+                    name: 'Declaration',
+                    attributes: {
+                      type: { id: 41, str: 'type', source_string: 'String', line: 2, col: 3 },
+                      name: { id: 39, str: 'identifier', source_string: 'bar', line: 2, col: 10 },
+                      expression: { id: 27, str: 'string', source_string: 'bar', line: 2, col: 16 },
+                    },
+                  }, {
+                    name: 'Declaration',
+                    attributes: {
+                      type: { id: 41, str: 'type', source_string: 'String', line: 3, col: 3 },
+                      name: { id: 39, str: 'identifier', source_string: 'baz', line: 3, col: 10 },
+                      expression: { id: 27, str: 'string', source_string: 'baz', line: 3, col: 16 },
+                    },
+                  }, {
+                    name: 'Call',
+                    attributes: {
+                      task: { id: 40, str: 'fqn', source_string: 'task1', line: 5, col: 8 },
+                      alias: null,
+                      body: {
+                        name: 'CallBody',
+                        attributes: {
+                          declarations: { list: [] },
+                          io: {
+                            list: [{
+                              name: 'Inputs',
+                              attributes: {
+                                map: {
+                                  list: [{
+                                    name: 'IOMapping',
+                                    attributes: {
+                                      key: {
+                                        id: 39,
+                                        str: 'identifier',
+                                        source_string: 'in',
+                                        line: 7,
+                                        col: 7,
+                                      },
+                                      value: {
+                                        name: 'FunctionCall',
+                                        attributes: {
+                                          name: {
+                                            id: 39,
+                                            str: 'identifier',
+                                            source_string: 'select_first',
+                                            line: 7,
+                                            col: 12,
+                                          },
+                                          params: {
+                                            list: [{
+                                              name: 'ArrayLiteral',
+                                              attributes: {
+                                                values: {
+                                                  list: [{
+                                                    id: 39,
+                                                    str: 'identifier',
+                                                    source_string: 'bar',
+                                                    line: 7,
+                                                    col: 26,
+                                                  }, {
+                                                    id: 39,
+                                                    str: 'identifier',
+                                                    source_string: 'baz',
+                                                    line: 7,
+                                                    col: 31,
+                                                  }],
+                                                },
+                                              },
+                                            }],
+                                          },
+                                        },
+                                      },
+                                    },
+                                  }],
+                                },
+                              },
+                            }],
+                          },
+                        },
+                      },
+                    },
+                  }],
+                },
+              },
+            },
+            isSubWorkflow: false,
+          },
+        },
+      };
+      const workflow = new WDLWorkflow(ast, context);
+
+      expect(workflow.workflowStep.children.task1.i.in.inputs[0].from.name).to.equal('bar');
+      expect(workflow.workflowStep.children.task1.i.in.inputs[1].from.name).to.equal('baz');
+    });
+
+    it('expect root workflow to have all declarations', () => {
+      /* eslint-disable no-template-curly-in-string */
+      const ast = {
+        name: { id: 39, str: 'identifier', source_string: 'foo', line: 1, col: 10 },
+        body: {
+          list: [{
+            name: 'Declaration',
+            attributes: {
+              type: { id: 41, str: 'type', source_string: 'String', line: 2, col: 3 },
+              name: { id: 39, str: 'identifier', source_string: 'bar', line: 2, col: 10 },
+              expression: { id: 27, str: 'string', source_string: 'bar', line: 2, col: 16 },
+            },
+          }, {
+            name: 'Declaration',
+            attributes: {
+              type: { id: 41, str: 'type', source_string: 'String', line: 3, col: 3 },
+              name: { id: 39, str: 'identifier', source_string: 'baz', line: 3, col: 10 },
+              expression: { id: 27, str: 'string', source_string: 'baz', line: 3, col: 16 },
+            },
+          }, {
+            name: 'Declaration',
+            attributes: {
+              type: { id: 41, str: 'type', source_string: 'String', line: 4, col: 3 },
+              name: { id: 39, str: 'identifier', source_string: 'newBar', line: 4, col: 10 },
+              expression: {
+                name: 'Add',
+                attributes: {
+                  lhs: {
+                    name: 'Add',
+                    attributes: {
+                      lhs: { id: 39, str: 'identifier', source_string: 'bar', line: 4, col: 19 },
+                      rhs: { id: 39, str: 'identifier', source_string: 'bar', line: 4, col: 25 },
+                    },
+                  },
+                  rhs: { id: 39, str: 'identifier', source_string: 'baz', line: 4, col: 31 },
+                },
+              },
+            },
+          }, {
+            name: 'Declaration',
+            attributes: {
+              type: { id: 41, str: 'type', source_string: 'String', line: 5, col: 3 },
+              name: { id: 39, str: 'identifier', source_string: 'newBaz', line: 5, col: 10 },
+              expression: { id: 39, str: 'identifier', source_string: 'baz', line: 5, col: 19 },
+            },
+          }, {
+            name: 'Declaration',
+            attributes: {
+              type: {
+                name: 'Type',
+                attributes: {
+                  name: { id: 41, str: 'type', source_string: 'Array', line: 6, col: 3 },
+                  subtype: { list: [{ id: 41, str: 'type', source_string: 'String', line: 6, col: 9 }] },
+                },
+              },
+              name: { id: 39, str: 'identifier', source_string: 'coll', line: 6, col: 17 },
+              expression: {
+                name: 'ArrayLiteral',
+                attributes: {
+                  values: {
+                    list: [{
+                      id: 39,
+                      str: 'identifier',
+                      source_string: 'bar',
+                      line: 6,
+                      col: 25,
+                    }, {
+                      id: 39,
+                      str: 'identifier',
+                      source_string: 'baz',
+                      line: 6,
+                      col: 30,
+                    }, {
+                      id: 39,
+                      str: 'identifier',
+                      source_string: 'newBaz',
+                      line: 6,
+                      col: 35,
+                    }, {
+                      id: 39,
+                      str: 'identifier',
+                      source_string: 'newBar',
+                      line: 6,
+                      col: 43,
+                    }],
+                  },
+                },
+              },
+            },
+          }, {
+            name: 'Scatter',
+            attributes: {
+              item: { id: 39, str: 'identifier', source_string: 'item', line: 8, col: 12 },
+              collection: { id: 39, str: 'identifier', source_string: 'coll', line: 8, col: 20 },
+              body: {
+                list: [{
+                  name: 'Call',
+                  attributes: {
+                    task: { id: 40, str: 'fqn', source_string: 'task1', line: 9, col: 10 },
+                    alias: null,
+                    body: {
+                      name: 'CallBody',
+                      attributes: {
+                        declarations: { list: [] },
+                        io: {
+                          list: [{
+                            name: 'Inputs',
+                            attributes: {
+                              map: {
+                                list: [{
+                                  name: 'IOMapping',
+                                  attributes: {
+                                    key: {
+                                      id: 39,
+                                      str: 'identifier',
+                                      source_string: 'in',
+                                      line: 11,
+                                      col: 9,
+                                    },
+                                    value: {
+                                      name: 'TernaryIf',
+                                      attributes: {
+                                        cond: {
+                                          name: 'FunctionCall',
+                                          attributes: {
+                                            name: {
+                                              id: 39,
+                                              str: 'identifier',
+                                              source_string: 'defined',
+                                              line: 11,
+                                              col: 17,
+                                            },
+                                            params: {
+                                              list: [{
+                                                id: 39,
+                                                str: 'identifier',
+                                                source_string: 'item',
+                                                line: 11,
+                                                col: 25,
+                                              }],
+                                            },
+                                          },
+                                        },
+                                        iftrue: {
+                                          id: 27,
+                                          str: 'string',
+                                          source_string: '${item} 1',
+                                          line: 11,
+                                          col: 36,
+                                        },
+                                        iffalse: {
+                                          id: 27,
+                                          str: 'string',
+                                          source_string: 'string',
+                                          line: 11,
+                                          col: 53,
+                                        },
+                                      },
+                                    },
+                                  },
+                                }],
+                              },
+                            },
+                          }],
+                        },
+                      },
+                    },
+                  },
+                }, {
+                  name: 'Declaration',
+                  attributes: {
+                    type: { id: 41, str: 'type', source_string: 'String', line: 13, col: 5 },
+                    name: { id: 39, str: 'identifier', source_string: 'res', line: 13, col: 12 },
+                    expression: {
+                      name: 'FunctionCall',
+                      attributes: {
+                        name: {
+                          id: 39,
+                          str: 'identifier',
+                          source_string: 'select_first',
+                          line: 13,
+                          col: 18,
+                        },
+                        params: {
+                          list: [{
+                            name: 'ArrayLiteral',
+                            attributes: {
+                              values: {
+                                list: [{
+                                  name: 'MemberAccess',
+                                  attributes: {
+                                    lhs: {
+                                      id: 39,
+                                      str: 'identifier',
+                                      source_string: 'task1',
+                                      line: 13,
+                                      col: 32,
+                                    },
+                                    rhs: {
+                                      id: 39,
+                                      str: 'identifier',
+                                      source_string: 'out',
+                                      line: 13,
+                                      col: 38,
+                                    },
+                                  },
+                                }, { id: 27, str: 'string', source_string: 'test', line: 13, col: 43 }],
+                              },
+                            },
+                          }],
+                        },
+                      },
+                    },
+                  },
+                }],
+              },
+            },
+          }, {
+            name: 'Call',
+            attributes: {
+              task: { id: 40, str: 'fqn', source_string: 'task2', line: 16, col: 8 },
+              alias: null,
+              body: {
+                name: 'CallBody',
+                attributes: {
+                  declarations: { list: [] },
+                  io: {
+                    list: [{
+                      name: 'Inputs',
+                      attributes: {
+                        map: {
+                          list: [{
+                            name: 'IOMapping',
+                            attributes: {
+                              key: {
+                                id: 39,
+                                str: 'identifier',
+                                source_string: 'in',
+                                line: 18,
+                                col: 7,
+                              },
+                              value: { id: 39, str: 'identifier', source_string: 'res', line: 18, col: 12 },
+                            },
+                          }],
+                        },
+                      },
+                    }],
+                  },
+                },
+              },
+            },
+          }],
+        },
+      };
+      const context = {
+        genericTaskCommandMap: [],
+        actionMap: {
+          task1: {
+            _handlers: {},
+            name: 'task1',
+            canHavePorts: true,
+            i: { in: { type: 'String', multi: false } },
+            o: { out: { type: 'String', default: 'output', multi: false } },
+            data: {},
+          },
+          task2: {
+            _handlers: {},
+            name: 'task2',
+            canHavePorts: true,
+            i: { in: { type: 'Array[String]', multi: false } },
+            o: {},
+            data: {},
+          },
+          foo: {
+            name: 'foo',
+            action: {
+              _handlers: { changed: [[null, null]], 'port-rename': [[null, null]] },
+              name: 'foo',
+              canHavePorts: true,
+              i: {},
+              o: {},
+              data: {},
+            },
+            parent: null,
+            children: {},
+            i: {
+              bar: { type: 'String', default: 'bar' },
+              baz: { type: 'String', default: 'baz' },
+              newBar: { type: 'String', default: 'bar + bar + baz' },
+              newBaz: { type: 'String', default: 'baz' },
+              coll: { type: 'Array[String]', default: '[bar, baz, newBaz, newBar]' },
+            },
+            o: {},
+            type: 'workflow',
+            ownDeclarations: {},
+            actions: {
+              foo: {
+                _handlers: { changed: [[null, null]], 'port-rename': [[null, null]] },
+                name: 'foo',
+                canHavePorts: true,
+                i: {},
+                o: {},
+                data: {},
+              },
+            },
+            declarations: {},
+            ast: {
+              name: 'Workflow',
+              attributes: {
+                name: { id: 39, str: 'identifier', source_string: 'foo', line: 1, col: 10 },
+                body: {
+                  list: [{
+                    name: 'Declaration',
+                    attributes: {
+                      type: { id: 41, str: 'type', source_string: 'String', line: 2, col: 3 },
+                      name: { id: 39, str: 'identifier', source_string: 'bar', line: 2, col: 10 },
+                      expression: { id: 27, str: 'string', source_string: 'bar', line: 2, col: 16 },
+                    },
+                  }, {
+                    name: 'Declaration',
+                    attributes: {
+                      type: { id: 41, str: 'type', source_string: 'String', line: 3, col: 3 },
+                      name: { id: 39, str: 'identifier', source_string: 'baz', line: 3, col: 10 },
+                      expression: { id: 27, str: 'string', source_string: 'baz', line: 3, col: 16 },
+                    },
+                  }, {
+                    name: 'Declaration',
+                    attributes: {
+                      type: { id: 41, str: 'type', source_string: 'String', line: 4, col: 3 },
+                      name: { id: 39, str: 'identifier', source_string: 'newBar', line: 4, col: 10 },
+                      expression: {
+                        name: 'Add',
+                        attributes: {
+                          lhs: {
+                            name: 'Add',
+                            attributes: {
+                              lhs: {
+                                id: 39,
+                                str: 'identifier',
+                                source_string: 'bar',
+                                line: 4,
+                                col: 19,
+                              },
+                              rhs: { id: 39, str: 'identifier', source_string: 'bar', line: 4, col: 25 },
+                            },
+                          },
+                          rhs: { id: 39, str: 'identifier', source_string: 'baz', line: 4, col: 31 },
+                        },
+                      },
+                    },
+                  }, {
+                    name: 'Declaration',
+                    attributes: {
+                      type: { id: 41, str: 'type', source_string: 'String', line: 5, col: 3 },
+                      name: { id: 39, str: 'identifier', source_string: 'newBaz', line: 5, col: 10 },
+                      expression: { id: 39, str: 'identifier', source_string: 'baz', line: 5, col: 19 },
+                    },
+                  }, {
+                    name: 'Declaration',
+                    attributes: {
+                      type: {
+                        name: 'Type',
+                        attributes: {
+                          name: { id: 41, str: 'type', source_string: 'Array', line: 6, col: 3 },
+                          subtype: {
+                            list: [{
+                              id: 41,
+                              str: 'type',
+                              source_string: 'String',
+                              line: 6,
+                              col: 9,
+                            }],
+                          },
+                        },
+                      },
+                      name: { id: 39, str: 'identifier', source_string: 'coll', line: 6, col: 17 },
+                      expression: {
+                        name: 'ArrayLiteral',
+                        attributes: {
+                          values: {
+                            list: [
+                              { id: 39, str: 'identifier', source_string: 'bar', line: 6, col: 25 },
+                              { id: 39, str: 'identifier', source_string: 'baz', line: 6, col: 30 },
+                              { id: 39, str: 'identifier', source_string: 'newBaz', line: 6, col: 35 },
+                              { id: 39, str: 'identifier', source_string: 'newBar', line: 6, col: 43 },
+                            ],
+                          },
+                        },
+                      },
+                    },
+                  }, {
+                    name: 'Scatter',
+                    attributes: {
+                      item: {
+                        id: 39,
+                        str: 'identifier',
+                        source_string: 'item',
+                        line: 8,
+                        col: 12,
+                      },
+                      collection: { id: 39, str: 'identifier', source_string: 'coll', line: 8, col: 20 },
+                      body: {
+                        list: [{
+                          name: 'Call',
+                          attributes: {
+                            task: {
+                              id: 40,
+                              str: 'fqn',
+                              source_string: 'task1',
+                              line: 9,
+                              col: 10,
+                            },
+                            alias: null,
+                            body: {
+                              name: 'CallBody',
+                              attributes: {
+                                declarations: { list: [] },
+                                io: {
+                                  list: [{
+                                    name: 'Inputs',
+                                    attributes: {
+                                      map: {
+                                        list: [{
+                                          name: 'IOMapping',
+                                          attributes: {
+                                            key: {
+                                              id: 39,
+                                              str: 'identifier',
+                                              source_string: 'in',
+                                              line: 11,
+                                              col: 9,
+                                            },
+                                            value: {
+                                              name: 'TernaryIf',
+                                              attributes: {
+                                                cond: {
+                                                  name: 'FunctionCall',
+                                                  attributes: {
+                                                    name: {
+                                                      id: 39,
+                                                      str: 'identifier',
+                                                      source_string: 'defined',
+                                                      line: 11,
+                                                      col: 17,
+                                                    },
+                                                    params: {
+                                                      list: [{
+                                                        id: 39,
+                                                        str: 'identifier',
+                                                        source_string: 'item',
+                                                        line: 11,
+                                                        col: 25,
+                                                      }],
+                                                    },
+                                                  },
+                                                },
+                                                iftrue: {
+                                                  id: 27,
+                                                  str: 'string',
+                                                  source_string: '${item} 1',
+                                                  line: 11,
+                                                  col: 36,
+                                                },
+                                                iffalse: {
+                                                  id: 27,
+                                                  str: 'string',
+                                                  source_string: 'string',
+                                                  line: 11,
+                                                  col: 53,
+                                                },
+                                              },
+                                            },
+                                          },
+                                        }],
+                                      },
+                                    },
+                                  }],
+                                },
+                              },
+                            },
+                          },
+                        }, {
+                          name: 'Declaration',
+                          attributes: {
+                            type: {
+                              id: 41,
+                              str: 'type',
+                              source_string: 'String',
+                              line: 13,
+                              col: 5,
+                            },
+                            name: { id: 39, str: 'identifier', source_string: 'res', line: 13, col: 12 },
+                            expression: {
+                              name: 'FunctionCall',
+                              attributes: {
+                                name: {
+                                  id: 39,
+                                  str: 'identifier',
+                                  source_string: 'select_first',
+                                  line: 13,
+                                  col: 18,
+                                },
+                                params: {
+                                  list: [{
+                                    name: 'ArrayLiteral',
+                                    attributes: {
+                                      values: {
+                                        list: [{
+                                          name: 'MemberAccess',
+                                          attributes: {
+                                            lhs: {
+                                              id: 39,
+                                              str: 'identifier',
+                                              source_string: 'task1',
+                                              line: 13,
+                                              col: 32,
+                                            },
+                                            rhs: {
+                                              id: 39,
+                                              str: 'identifier',
+                                              source_string: 'out',
+                                              line: 13,
+                                              col: 38,
+                                            },
+                                          },
+                                        }, { id: 27, str: 'string', source_string: 'test', line: 13, col: 43 }],
+                                      },
+                                    },
+                                  }],
+                                },
+                              },
+                            },
+                          },
+                        }],
+                      },
+                    },
+                  }, {
+                    name: 'Call',
+                    attributes: {
+                      task: { id: 40, str: 'fqn', source_string: 'task2', line: 16, col: 8 },
+                      alias: null,
+                      body: {
+                        name: 'CallBody',
+                        attributes: {
+                          declarations: { list: [] },
+                          io: {
+                            list: [{
+                              name: 'Inputs',
+                              attributes: {
+                                map: {
+                                  list: [{
+                                    name: 'IOMapping',
+                                    attributes: {
+                                      key: {
+                                        id: 39,
+                                        str: 'identifier',
+                                        source_string: 'in',
+                                        line: 18,
+                                        col: 7,
+                                      },
+                                      value: {
+                                        id: 39,
+                                        str: 'identifier',
+                                        source_string: 'res',
+                                        line: 18,
+                                        col: 12,
+                                      },
+                                    },
+                                  }],
+                                },
+                              },
+                            }],
+                          },
+                        },
+                      },
+                    },
+                  }],
+                },
+              },
+            },
+            isSubWorkflow: false,
+          },
+        },
+      };
+      /* eslint-enable no-template-curly-in-string */
+      const workflow = new WDLWorkflow(ast, context);
+
+      expect(workflow.workflowStep.declarations).to.have.all.keys(['bar', 'baz', 'newBar', 'newBaz', 'coll', 'res']);
+    });
+
+    it('throws an error when some declaration refers to undeclared variable identifier in a function call', () => {
+      const ast = {
+        name: { id: 39, str: 'identifier', source_string: 'foo', line: 1, col: 10 },
+        body: {
+          list: [{
+            name: 'Declaration',
+            attributes: {
+              type: { id: 41, str: 'type', source_string: 'Float', line: 2, col: 3 },
+              name: { id: 39, str: 'identifier', source_string: 'bar', line: 2, col: 9 },
+              expression: { id: 17, str: 'float', source_string: '9.54', line: 2, col: 15 },
+            },
+          }, {
+            name: 'Declaration',
+            attributes: {
+              type: { id: 41, str: 'type', source_string: 'Int', line: 3, col: 3 },
+              name: { id: 39, str: 'identifier', source_string: 'baz', line: 3, col: 7 },
+              expression: {
+                name: 'FunctionCall',
+                attributes: {
+                  name: { id: 39, str: 'identifier', source_string: 'ceil', line: 3, col: 13 },
+                  params: {
+                    list: [{
+                      id: 39,
+                      str: 'identifier',
+                      source_string: 'undeclaredBar',
+                      line: 3,
+                      col: 18,
+                    }],
+                  },
+                },
+              },
+            },
+          }],
+        },
+      };
+      const context = {
+        genericTaskCommandMap: [],
+        actionMap: {
+          foo: {
+            name: 'foo',
+            action: {
+              _handlers: { changed: [[null, null]], 'port-rename': [[null, null]] },
+              name: 'foo',
+              canHavePorts: true,
+              i: {},
+              o: {},
+              data: {},
+            },
+            parent: null,
+            children: {},
+            i: {
+              bar: { type: 'Float', default: '9.54' },
+              baz: { type: 'Int', default: 'ceil(undeclaredBar)' },
+            },
+            o: {},
+            type: 'workflow',
+            ownDeclarations: {},
+            actions: {
+              foo: {
+                _handlers: { changed: [[null, null]], 'port-rename': [[null, null]] },
+                name: 'foo',
+                canHavePorts: true,
+                i: {},
+                o: {},
+                data: {},
+              },
+            },
+            declarations: {},
+            ast: {
+              name: 'Workflow',
+              attributes: {
+                name: { id: 39, str: 'identifier', source_string: 'foo', line: 1, col: 10 },
+                body: {
+                  list: [{
+                    name: 'Declaration',
+                    attributes: {
+                      type: { id: 41, str: 'type', source_string: 'Float', line: 2, col: 3 },
+                      name: { id: 39, str: 'identifier', source_string: 'bar', line: 2, col: 9 },
+                      expression: { id: 17, str: 'float', source_string: '9.54', line: 2, col: 15 },
+                    },
+                  }, {
+                    name: 'Declaration',
+                    attributes: {
+                      type: { id: 41, str: 'type', source_string: 'Int', line: 3, col: 3 },
+                      name: { id: 39, str: 'identifier', source_string: 'baz', line: 3, col: 7 },
+                      expression: {
+                        name: 'FunctionCall',
+                        attributes: {
+                          name: {
+                            id: 39,
+                            str: 'identifier',
+                            source_string: 'ceil',
+                            line: 3,
+                            col: 13,
+                          },
+                          params: {
+                            list: [{
+                              id: 39,
+                              str: 'identifier',
+                              source_string: 'undeclaredBar',
+                              line: 3,
+                              col: 18,
+                            }],
+                          },
+                        },
+                      },
+                    },
+                  }],
+                },
+              },
+            },
+            isSubWorkflow: false,
+          },
+        },
+      };
+
+      expect(() => new WDLWorkflow(ast, context)).to.throws(WDLParserError);
+    });
+
+    it('throws an error when some declaration refers to undeclared call in a function call', () => {
+      const ast = {
+        name: { id: 39, str: 'identifier', source_string: 'foo', line: 1, col: 10 },
+        body: {
+          list: [{
+            name: 'Declaration',
+            attributes: {
+              type: { id: 41, str: 'type', source_string: 'Float', line: 2, col: 3 },
+              name: { id: 39, str: 'identifier', source_string: 'bar', line: 2, col: 9 },
+              expression: { id: 17, str: 'float', source_string: '9.54', line: 2, col: 15 },
+            },
+          }, {
+            name: 'Declaration',
+            attributes: {
+              type: { id: 41, str: 'type', source_string: 'Int', line: 3, col: 3 },
+              name: { id: 39, str: 'identifier', source_string: 'baz', line: 3, col: 7 },
+              expression: {
+                name: 'FunctionCall',
+                attributes: {
+                  name: { id: 39, str: 'identifier', source_string: 'ceil', line: 3, col: 13 },
+                  params: {
+                    list: [{
+                      name: 'MemberAccess',
+                      attributes: {
+                        lhs: {
+                          id: 39,
+                          str: 'identifier',
+                          source_string: 'undeclaredCall',
+                          line: 3,
+                          col: 18,
+                        },
+                        rhs: { id: 39, str: 'identifier', source_string: 'undeclaredBar', line: 3, col: 33 },
+                      },
+                    }],
+                  },
+                },
+              },
+            },
+          }],
+        },
+      };
+      const context = {
+        genericTaskCommandMap: [],
+        actionMap: {
+          foo: {
+            name: 'foo',
+            action: {
+              _handlers: { changed: [[null, null]], 'port-rename': [[null, null]] },
+              name: 'foo',
+              canHavePorts: true,
+              i: {},
+              o: {},
+              data: {},
+            },
+            parent: null,
+            children: {},
+            i: {
+              bar: { type: 'Float', default: '9.54' },
+              baz: { type: 'Int', default: 'ceil(undeclaredCall.undeclaredBar)' },
+            },
+            o: {},
+            type: 'workflow',
+            ownDeclarations: {},
+            actions: {
+              foo: {
+                _handlers: { changed: [[null, null]], 'port-rename': [[null, null]] },
+                name: 'foo',
+                canHavePorts: true,
+                i: {},
+                o: {},
+                data: {},
+              },
+            },
+            declarations: {},
+            ast: {
+              name: 'Workflow',
+              attributes: {
+                name: { id: 39, str: 'identifier', source_string: 'foo', line: 1, col: 10 },
+                body: {
+                  list: [{
+                    name: 'Declaration',
+                    attributes: {
+                      type: { id: 41, str: 'type', source_string: 'Float', line: 2, col: 3 },
+                      name: { id: 39, str: 'identifier', source_string: 'bar', line: 2, col: 9 },
+                      expression: { id: 17, str: 'float', source_string: '9.54', line: 2, col: 15 },
+                    },
+                  }, {
+                    name: 'Declaration',
+                    attributes: {
+                      type: { id: 41, str: 'type', source_string: 'Int', line: 3, col: 3 },
+                      name: { id: 39, str: 'identifier', source_string: 'baz', line: 3, col: 7 },
+                      expression: {
+                        name: 'FunctionCall',
+                        attributes: {
+                          name: {
+                            id: 39,
+                            str: 'identifier',
+                            source_string: 'ceil',
+                            line: 3,
+                            col: 13,
+                          },
+                          params: {
+                            list: [{
+                              name: 'MemberAccess',
+                              attributes: {
+                                lhs: {
+                                  id: 39,
+                                  str: 'identifier',
+                                  source_string: 'undeclaredCall',
+                                  line: 3,
+                                  col: 18,
+                                },
+                                rhs: {
+                                  id: 39,
+                                  str: 'identifier',
+                                  source_string: 'undeclaredBar',
+                                  line: 3,
+                                  col: 33,
+                                },
+                              },
+                            }],
+                          },
+                        },
+                      },
+                    },
+                  }],
+                },
+              },
+            },
+            isSubWorkflow: false,
+          },
+        },
+      };
+
+      expect(() => new WDLWorkflow(ast, context)).to.throws(WDLParserError);
+    });
+
+    it('throws an error when some declaration refers to undeclared member access variable in a function call', () => {
+      const ast = {
+        name: { id: 39, str: 'identifier', source_string: 'foo', line: 1, col: 10 },
+        body: {
+          list: [{
+            name: 'Declaration',
+            attributes: {
+              type: { id: 41, str: 'type', source_string: 'Float', line: 2, col: 3 },
+              name: { id: 39, str: 'identifier', source_string: 'bar', line: 2, col: 9 },
+              expression: { id: 17, str: 'float', source_string: '9.54', line: 2, col: 15 },
+            },
+          }, {
+            name: 'Call',
+            attributes: {
+              task: { id: 40, str: 'fqn', source_string: 'task1', line: 3, col: 8 },
+              alias: null,
+              body: {
+                name: 'CallBody',
+                attributes: {
+                  declarations: { list: [] },
+                  io: {
+                    list: [{
+                      name: 'Inputs',
+                      attributes: {
+                        map: {
+                          list: [{
+                            name: 'IOMapping',
+                            attributes: {
+                              key: {
+                                id: 39,
+                                str: 'identifier',
+                                source_string: 'in',
+                                line: 5,
+                                col: 7,
+                              },
+                              value: { id: 39, str: 'identifier', source_string: 'bar', line: 5, col: 12 },
+                            },
+                          }],
+                        },
+                      },
+                    }],
+                  },
+                },
+              },
+            },
+          }, {
+            name: 'Declaration',
+            attributes: {
+              type: { id: 41, str: 'type', source_string: 'Int', line: 7, col: 3 },
+              name: { id: 39, str: 'identifier', source_string: 'baz', line: 7, col: 7 },
+              expression: {
+                name: 'FunctionCall',
+                attributes: {
+                  name: { id: 39, str: 'identifier', source_string: 'ceil', line: 7, col: 13 },
+                  params: {
+                    list: [{
+                      name: 'MemberAccess',
+                      attributes: {
+                        lhs: {
+                          id: 39,
+                          str: 'identifier',
+                          source_string: 'task1',
+                          line: 7,
+                          col: 18,
+                        },
+                        rhs: {
+                          id: 39,
+                          str: 'identifier',
+                          source_string: 'undeclaredOutput',
+                          line: 7,
+                          col: 24,
+                        },
+                      },
+                    }],
+                  },
+                },
+              },
+            },
+          }],
+        },
+      };
+      const context = {
+        genericTaskCommandMap: [],
+        actionMap: {
+          task1: {
+            _handlers: {},
+            name: 'task1',
+            canHavePorts: true,
+            i: { in: { type: 'Float', multi: false } },
+            o: {},
+            data: {},
+          },
+          foo: {
+            name: 'foo',
+            action: {
+              _handlers: { changed: [[null, null]], 'port-rename': [[null, null]] },
+              name: 'foo',
+              canHavePorts: true,
+              i: {},
+              o: {},
+              data: {},
+            },
+            parent: null,
+            children: {},
+            i: {
+              bar: { type: 'Float', default: '9.54' },
+              baz: { type: 'Int', default: 'ceil(task1.undeclaredOutput)' },
+            },
+            o: {},
+            type: 'workflow',
+            ownDeclarations: {},
+            actions: {
+              foo: {
+                _handlers: { changed: [[null, null]], 'port-rename': [[null, null]] },
+                name: 'foo',
+                canHavePorts: true,
+                i: {},
+                o: {},
+                data: {},
+              },
+            },
+            declarations: {},
+            ast: {
+              name: 'Workflow',
+              attributes: {
+                name: { id: 39, str: 'identifier', source_string: 'foo', line: 1, col: 10 },
+                body: {
+                  list: [{
+                    name: 'Declaration',
+                    attributes: {
+                      type: { id: 41, str: 'type', source_string: 'Float', line: 2, col: 3 },
+                      name: { id: 39, str: 'identifier', source_string: 'bar', line: 2, col: 9 },
+                      expression: { id: 17, str: 'float', source_string: '9.54', line: 2, col: 15 },
+                    },
+                  }, {
+                    name: 'Call',
+                    attributes: {
+                      task: { id: 40, str: 'fqn', source_string: 'task1', line: 3, col: 8 },
+                      alias: null,
+                      body: {
+                        name: 'CallBody',
+                        attributes: {
+                          declarations: { list: [] },
+                          io: {
+                            list: [{
+                              name: 'Inputs',
+                              attributes: {
+                                map: {
+                                  list: [{
+                                    name: 'IOMapping',
+                                    attributes: {
+                                      key: {
+                                        id: 39,
+                                        str: 'identifier',
+                                        source_string: 'in',
+                                        line: 5,
+                                        col: 7,
+                                      },
+                                      value: {
+                                        id: 39,
+                                        str: 'identifier',
+                                        source_string: 'bar',
+                                        line: 5,
+                                        col: 12,
+                                      },
+                                    },
+                                  }],
+                                },
+                              },
+                            }],
+                          },
+                        },
+                      },
+                    },
+                  }, {
+                    name: 'Declaration',
+                    attributes: {
+                      type: { id: 41, str: 'type', source_string: 'Int', line: 7, col: 3 },
+                      name: { id: 39, str: 'identifier', source_string: 'baz', line: 7, col: 7 },
+                      expression: {
+                        name: 'FunctionCall',
+                        attributes: {
+                          name: {
+                            id: 39,
+                            str: 'identifier',
+                            source_string: 'ceil',
+                            line: 7,
+                            col: 13,
+                          },
+                          params: {
+                            list: [{
+                              name: 'MemberAccess',
+                              attributes: {
+                                lhs: {
+                                  id: 39,
+                                  str: 'identifier',
+                                  source_string: 'task1',
+                                  line: 7,
+                                  col: 18,
+                                },
+                                rhs: {
+                                  id: 39,
+                                  str: 'identifier',
+                                  source_string: 'undeclaredOutput',
+                                  line: 7,
+                                  col: 24,
+                                },
+                              },
+                            }],
+                          },
+                        },
+                      },
+                    },
+                  }],
+                },
+              },
+            },
+            isSubWorkflow: false,
+          },
+        },
+      };
+
+      expect(() => new WDLWorkflow(ast, context)).to.throws(WDLParserError);
+    });
+
     it('throws error when workflow declarations are obtained not only at start', () => {
       const ast = {
         name: {
diff --git a/test/parser/WDL/parseTest.js b/test/parser/WDL/parseTest.js
index 037afeb..faef003 100644
--- a/test/parser/WDL/parseTest.js
+++ b/test/parser/WDL/parseTest.js
@@ -26,21 +26,6 @@ workflow foo {
     return expect(parse(src)).to.be.fulfilled;
   });
 
-  it('returns with error flag if source syntax is incorrect', () => {
-    const src = `
-workflow foo {
-  File a
-  call b
-  File c
-}
-
-task b {
-  File a
-}`;
-
-    return expect(parse(src)).to.be.rejected;
-  });
-
   it('requires to parse valid wdl script', () => {
     const flow = new Workflow('example1', {
       i: {
diff --git a/test/parser/WDL/utils/renaming_utilsTest.js b/test/parser/WDL/utils/renaming_utilsTest.js
new file mode 100644
index 0000000..9ade7bf
--- /dev/null
+++ b/test/parser/WDL/utils/renaming_utilsTest.js
@@ -0,0 +1,380 @@
+import { expect } from 'chai';
+
+import { renameExpression, replaceSplitter } from '../../../../src/parser/WDL/utils/renaming_utils';
+
+describe('parser/WDL/renaming_utils', () => {
+  describe('.replaceSplitter()', () => {
+    it('expect to replace splitter in source string', () => {
+      expect(replaceSplitter('ns.name')).to.equal('ns_name');
+      expect(replaceSplitter('ns.name.var')).to.equal('ns_name.var');
+    });
+  });
+
+  describe('.renameExpression()', () => {
+    it('requires an empty ast', () => {
+      const astUndefined = undefined;
+      renameExpression(astUndefined);
+      expect(astUndefined).to.equal(undefined);
+      const astNull = null;
+      renameExpression(astNull);
+      expect(astNull).to.equal(null);
+      const astEmpty = '';
+      renameExpression(astEmpty);
+      expect(astEmpty).to.equal('');
+    });
+
+    it('renames an identifier within expression with map literal and function call', () => {
+      const ast = {
+        name: 'MapLiteral',
+        attributes: {
+          map: {
+            list: [
+              {
+                name: 'MapLiteralKv',
+                attributes: {
+                  key: {
+                    id: 2,
+                    str: 'integer',
+                    source_string: '1',
+                    line: 18,
+                    col: 28,
+                  },
+                  value: {
+                    id: 18,
+                    str: 'string',
+                    source_string: 'a',
+                    line: 18,
+                    col: 32,
+                  },
+                },
+              },
+              {
+                name: 'MapLiteralKv',
+                attributes: {
+                  key: {
+                    id: 2,
+                    str: 'integer',
+                    source_string: '3',
+                    line: 18,
+                    col: 37,
+                  },
+                  value: {
+                    name: 'FunctionCall',
+                    attributes: {
+                      name: {
+                        id: 14,
+                        str: 'identifier',
+                        source_string: 'read_string',
+                        line: 18,
+                        col: 41,
+                      },
+                      params: {
+                        list: [
+                          {
+                            name: 'MemberAccess',
+                            attributes: {
+                              lhs: {
+                                id: 14,
+                                str: 'identifier',
+                                source_string: 'bar',
+                                line: 16,
+                                col: 16,
+                              },
+                              rhs: {
+                                id: 14,
+                                str: 'identifier',
+                                source_string: 'out1',
+                                line: 16,
+                                col: 20,
+                              },
+                            },
+                          },
+                          {
+                            id: 2,
+                            str: 'integer',
+                            source_string: '2',
+                            line: 18,
+                            col: 56,
+                          },
+                        ],
+                      },
+                    },
+                  },
+                },
+              },
+            ],
+          },
+        },
+      };
+      const prefix = 'pre_';
+      const initialCalls = ['ns.bar', 'ns2.baz'];
+
+      renameExpression(ast, prefix, initialCalls);
+
+      expect(ast.attributes.map.list[1].attributes.value.attributes.params.list[0].attributes.lhs.source_string).to.equal('pre_ns_bar');
+    });
+
+    it('renames multiple identifiers within expression with array and object literals', () => {
+      const ast = {
+        name: 'ArrayLiteral',
+        attributes: {
+          values: {
+            list: [
+              {
+                name: 'ObjectLiteral',
+                attributes: {
+                  map: {
+                    list: [
+                      {
+                        name: 'ObjectKV',
+                        attributes: {
+                          key: {
+                            id: 14,
+                            str: 'identifier',
+                            source_string: 'o1',
+                            line: 17,
+                            col: 25,
+                          },
+                          value: {
+                            name: 'MemberAccess',
+                            attributes: {
+                              lhs: {
+                                id: 14,
+                                str: 'identifier',
+                                source_string: 'bar',
+                                line: 17,
+                                col: 30,
+                              },
+                              rhs: {
+                                id: 14,
+                                str: 'identifier',
+                                source_string: 'out1',
+                                line: 17,
+                                col: 34,
+                              },
+                            },
+                          },
+                        },
+                      },
+                      {
+                        name: 'ObjectKV',
+                        attributes: {
+                          key: {
+                            id: 14,
+                            str: 'identifier',
+                            source_string: 'o1',
+                            line: 17,
+                            col: 25,
+                          },
+                          value: {
+                            name: 'MemberAccess',
+                            attributes: {
+                              lhs: {
+                                id: 14,
+                                str: 'identifier',
+                                source_string: 'bar',
+                                line: 17,
+                                col: 45,
+                              },
+                              rhs: {
+                                id: 14,
+                                str: 'identifier',
+                                source_string: 'out2',
+                                line: 17,
+                                col: 49,
+                              },
+                            },
+                          },
+                        },
+                      },
+                    ],
+                  },
+                },
+              },
+              {
+                name: 'MemberAccess',
+                attributes: {
+                  lhs: {
+                    id: 14,
+                    str: 'identifier',
+                    source_string: 'baz',
+                    line: 17,
+                    col: 30,
+                  },
+                  rhs: {
+                    id: 14,
+                    str: 'identifier',
+                    source_string: 'out',
+                    line: 17,
+                    col: 34,
+                  },
+                },
+              },
+            ],
+          },
+        },
+      };
+      const prefix = 'pre_';
+      const initialCalls = ['ns.bar', 'ns2.baz'];
+
+      renameExpression(ast, prefix, initialCalls);
+
+      expect(ast.attributes.values.list[0].attributes.map.list[0].attributes.value.attributes.lhs.source_string).to.equal('pre_ns_bar');
+      expect(ast.attributes.values.list[0].attributes.map.list[1].attributes.value.attributes.lhs.source_string).to.equal('pre_ns_bar');
+      expect(ast.attributes.values.list[1].attributes.lhs.source_string).to.equal('pre_ns2_baz');
+    });
+
+    it('renames an identifier within expression with binary and unary operations', () => {
+      const ast = {
+        name: 'Add',
+        attributes: {
+          lhs: {
+            name: 'LogicalNot',
+            attributes: {
+              expression: {
+                name: 'MemberAccess',
+                attributes: {
+                  lhs: {
+                    id: 14,
+                    str: 'identifier',
+                    source_string: 'baz',
+                    line: 16,
+                    col: 16,
+                  },
+                  rhs: {
+                    id: 14,
+                    str: 'identifier',
+                    source_string: 'out1',
+                    line: 16,
+                    col: 20,
+                  },
+                },
+              },
+            },
+          },
+          rhs: {
+            name: 'Multiply',
+            attributes: {
+              lhs: {
+                id: 2,
+                str: 'integer',
+                source_string: '5',
+                line: 14,
+                col: 17,
+              },
+              rhs: {
+                id: 2,
+                str: 'integer',
+                source_string: '4',
+                line: 14,
+                col: 22,
+              },
+            },
+          },
+        },
+      };
+      const prefix = 'pre_';
+      const initialCalls = ['ns.baz'];
+
+      renameExpression(ast, prefix, initialCalls);
+
+      expect(ast.attributes.lhs.attributes.expression.attributes.lhs.source_string).to.equal('pre_ns_baz');
+    });
+
+    it('renames an identifier within expression with tuple literal and ternary', () => {
+      const ast = {
+        name: 'TernaryIf',
+        attributes: {
+          cond: {
+            name: 'TupleLiteral',
+            attributes: {
+              values: {
+                list: [
+                  {
+                    name: 'LogicalAnd',
+                    attributes: {
+                      lhs: {
+                        name: 'LogicalNot',
+                        attributes: {
+                          expression: {
+                            name: 'MemberAccess',
+                            attributes: {
+                              lhs: {
+                                id: 14,
+                                str: 'identifier',
+                                source_string: 'baz',
+                                line: 16,
+                                col: 16,
+                              },
+                              rhs: {
+                                id: 14,
+                                str: 'identifier',
+                                source_string: 'out1',
+                                line: 16,
+                                col: 20,
+                              },
+                            },
+                          },
+                        },
+                      },
+                      rhs: {
+                        name: 'MemberAccess',
+                        attributes: {
+                          lhs: {
+                            id: 14,
+                            str: 'identifier',
+                            source_string: 'foo',
+                            line: 16,
+                            col: 16,
+                          },
+                          rhs: {
+                            id: 14,
+                            str: 'identifier',
+                            source_string: 'out1',
+                            line: 16,
+                            col: 20,
+                          },
+                        },
+                      },
+                    },
+                  },
+                ],
+              },
+            },
+          },
+          iftrue: {
+            name: 'LogicalNot',
+            attributes: {
+              expression: {
+                id: 2,
+                str: 'integer',
+                source_string: '2',
+                line: 14,
+                col: 12,
+              },
+            },
+          },
+          iffalse: {
+            name: 'LogicalNot',
+            attributes: {
+              expression: {
+                id: 2,
+                str: 'integer',
+                source_string: '3',
+                line: 14,
+                col: 12,
+              },
+            },
+          },
+        },
+      };
+      const prefix = 'pre_';
+      const initialCalls = ['ns.foo', 'ns.bar', 'ns.baz'];
+
+      renameExpression(ast, prefix, initialCalls);
+
+      expect(ast.attributes.cond.attributes.values.list[0].attributes.lhs.attributes.expression.attributes.lhs.source_string).to.equal('pre_ns_baz');
+      expect(ast.attributes.cond.attributes.values.list[0].attributes.rhs.attributes.lhs.source_string).to.equal('pre_ns_foo');
+    });
+  });
+});
diff --git a/test/parser/parseTest.js b/test/parser/parseTest.js
index 4cf7232..b43b040 100644
--- a/test/parser/parseTest.js
+++ b/test/parser/parseTest.js
@@ -65,8 +65,11 @@ workflow RootWorkflow {
         resolve(data);
       }
     });
-  }).then(data => parse(wdl, { zipFile: data, subWfDetailing: '*', recursionDepth: 10 }))).to.be.fulfilled);
+  }).then(data => parse(wdl, { zipFile: data, subWfDetailing: ['*'], recursionDepth: 10 }))).to.be.fulfilled);
 
   it('returns with error if source zip is incorrect', () =>
     expect(parse(wdl, { zipFile: 'test' })).to.be.rejectedWith('Error'));
+
+  it('returns with error if no wdl presented', () =>
+    expect(parse('')).to.be.rejected);
 });