Replace = with as

src/language/__tests__/schema-kitchen-sink.graphql

@@ -41,7 +41,7 @@ union AnnotatedUnionTwo @onUnion = | A | B
 
 scalar CustomScalar
 
-scalar StringEncodedCustomScalar = String
+scalar StringEncodedCustomScalar as String
 
 scalar AnnotatedScalar @onScalar
 

src/language/__tests__/schema-printer-test.js

@@ -87,7 +87,7 @@ union AnnotatedUnionTwo @onUnion = A | B
 
 scalar CustomScalar
 
-scalar StringEncodedCustomScalar = String
+scalar StringEncodedCustomScalar as String
 
 scalar AnnotatedScalar @onScalar
 

src/language/parser.js

@@ -784,14 +784,14 @@ function parseOperationTypeDefinition(
 }
 
 /**
- * ScalarTypeDefinition : scalar Name ScalarOfType? Directives?
- * ScalarOfType : = NamedType
+ * ScalarTypeDefinition : scalar Name SerializeAsType? Directives?
+ * SerializeAsType : as NamedType
  */
 function parseScalarTypeDefinition(lexer: Lexer<*>): ScalarTypeDefinitionNode {
   const start = lexer.token;
   expectKeyword(lexer, 'scalar');
   const name = parseName(lexer);
-  const type = skip(lexer, TokenKind.EQUALS) ? parseNamedType(lexer) : null;
+  const type = skipKeyword(lexer, 'as') ? parseNamedType(lexer) : null;
   const directives = parseDirectives(lexer);
   return {
     kind: SCALAR_TYPE_DEFINITION,
@@ -1133,10 +1133,24 @@ function expect(lexer: Lexer<*>, kind: string): Token {
 }
 
 /**
- * If the next token is a keyword with the given value, return that token after
+ * If the next token is a keyword with the given value, return true after
  * advancing the lexer. Otherwise, do not change the parser state and return
  * false.
  */
+function skipKeyword(lexer: Lexer<*>, value: string): boolean {
+  const token = lexer.token;
+  const match = token.kind === TokenKind.NAME && token.value === value;
+  if (match) {
+    lexer.advance();
+  }
+  return match;
+}
+
+/**
+ * If the next token is a keyword with the given value, return that token after
+ * advancing the lexer. Otherwise, do not change the parser state and throw
+ * an error.
+ */
 function expectKeyword(lexer: Lexer<*>, value: string): Token {
   const token = lexer.token;
   if (token.kind === TokenKind.NAME && token.value === value) {

src/language/printer.js

@@ -106,7 +106,7 @@ const printDocASTReducer = {
     operation + ': ' + type,
 
   ScalarTypeDefinition: ({ name, type, directives }) =>
-    join([ 'scalar', name, wrap('= ', type), join(directives, ' ') ], ' '),
+    join([ 'scalar', name, wrap('as ', type), join(directives, ' ') ], ' '),
 
   ObjectTypeDefinition: ({ name, interfaces, directives, fields }) =>
     join([

src/type/__tests__/introspection-test.js

@@ -1313,8 +1313,9 @@ describe('Introspection', () => {
             'An enum describing what kind of type a given `__Type` is.',
           enumValues: [
             {
-              description: 'Indicates this type is a scalar. ' +
-                           '`ofType` is a valid field.',
+              description:
+                'Indicates this type is a scalar. ' +
+                  '`ofType` may represent how this scalar is serialized.',
               name: 'SCALAR'
             },
             {

src/type/introspection.js

@@ -207,8 +207,8 @@ export const __Type = new GraphQLObjectType({
     'The fundamental unit of any GraphQL Schema is the type. There are ' +
     'many kinds of types in GraphQL as represented by the `__TypeKind` enum.' +
     '\n\nDepending on the kind of a type, certain fields describe ' +
-    'information about that type. Scalar types provide no information ' +
-    'beyond a name and description, while Enum types provide their values. ' +
+    'information about that type. Scalar types provide a name, description' +
+    'and how they serialize, while Enum types provide their possible values. ' +
     'Object and Interface types provide the fields they describe. Abstract ' +
     'types, Union and Interface, provide the Object types possible ' +
     'at runtime. List and NonNull types compose other types.',
@@ -382,7 +382,7 @@ export const __TypeKind = new GraphQLEnumType({
     SCALAR: {
       value: TypeKind.SCALAR,
       description: 'Indicates this type is a scalar. ' +
-                   '`ofType` is a valid field.'
+                   '`ofType` may represent how this scalar is serialized.'
     },
     OBJECT: {
       value: TypeKind.OBJECT,

src/utilities/__tests__/schemaPrinter-test.js

@@ -554,25 +554,15 @@ describe('Type System Printer', () => {
         query: Root
       }
 
-<<<<<<< HEAD
+      scalar Even as Int
+
       scalar Odd
 
       type Root {
+        even: Even
         odd: Odd
       }
     `);
-=======
-scalar Even = Int
-
-scalar Odd
-
-type Root {
-  even: Even
-  odd: Odd
-}
-`
-     );
->>>>>>> RFC: Define custom scalars in terms of built-in scalars.
   });
 
   it('Enum', () => {
@@ -775,10 +765,10 @@ type Root {
       # types in GraphQL as represented by the \`__TypeKind\` enum.
       #
       # Depending on the kind of a type, certain fields describe information about that
-      # type. Scalar types provide no information beyond a name and description, while
-      # Enum types provide their values. Object and Interface types provide the fields
-      # they describe. Abstract types, Union and Interface, provide the Object types
-      # possible at runtime. List and NonNull types compose other types.
+      # type. Scalar types provide a name, descriptionand how they serialize, while Enum
+      # types provide their possible values. Object and Interface types provide the
+      # fields they describe. Abstract types, Union and Interface, provide the Object
+      # types possible at runtime. List and NonNull types compose other types.
       type __Type {
         description: String
         enumValues(includeDeprecated: Boolean = false): [__EnumValue!]
@@ -793,7 +783,7 @@ type Root {
 
       # An enum describing what kind of type a given \`__Type\` is.
       enum __TypeKind {
-        # Indicates this type is a scalar. \`ofType\` is a valid field.
+        # Indicates this type is a scalar. \`ofType\` may represent how this scalar is serialized.
         SCALAR
 
         # Indicates this type is an object. \`fields\` and \`interfaces\` are valid fields.

src/utilities/schemaPrinter.js

@@ -153,9 +153,9 @@ export function printType(type: GraphQLType): string {
 }
 
 function printScalar(type: GraphQLScalarType): string {
-  const ofType = type.ofType ? ` = ${type.ofType.name}` : '';
+  const serializeAsType = type.ofType ? ` as ${type.ofType.name}` : '';
   return printDescription(type) +
-    `scalar ${type.name}${ofType}`;
+    `scalar ${type.name}${serializeAsType}`;
 }
 
 function printObject(type: GraphQLObjectType): string {