feat(pointfree-lang): implement dynamic var scoping & local var grammar

- add loadvar/storevar/beginvar/endvar word fns
- add `^{ x y }` syntax to autobind word local vars
- update var lookups/updates to use scope/binding stack (per var)
- update visitWord() to inject local var handling (if needed)
- update ensureEnv() to prepare var stacks
- add finalizeEnv() to resolve final var results and remove var stacks
- fix aliases
- add docs

packages/pointfree-lang/src/api.ts

@@ -6,6 +6,7 @@ export interface ASTNode {
     body: any;
     loc: [number, number];
     id?: string;
+    locals: string[];
 }
 
 export interface VisitorState {
@@ -50,11 +51,11 @@ export const ALIASES: IObjectOf<pf.StackFn> = {
     "v*": pf.vmul,
     "v/": pf.vdiv,
     "=": pf.eq,
-    "!=": pf.gteq,
+    "not=": pf.neq,
     "<=": pf.lteq,
     ">=": pf.gteq,
-    "<": pf.lteq,
-    ">": pf.gteq,
+    "<": pf.lt,
+    ">": pf.gt,
     "pos?": pf.ispos,
     "neg?": pf.isneg,
     "nil?": pf.isnull,

packages/pointfree-lang/src/grammar.pegjs

@@ -41,10 +41,18 @@ NonWordExpr
     ) _ { return ast(expr); }
 
 Word
-    = ":" __ id:Sym body:NonWordExpr+ ";" {
-        return { type: NodeType.WORD, id: id.id, body};
+    = ":" __ id:Sym locals:LocalVars? body:NonWordExpr+ ";" {
+        return { type: NodeType.WORD, id: id.id, locals, body};
     }
 
+LocalVars
+	= _ "^{" body:SymList+ "}" {
+    	return body;
+    }
+
+SymList
+	= _ id:Sym _ { return id.id; }
+
 Array
     = "[" body:NonWordExpr* "]" {
         return { type: NodeType.ARRAY, body };
@@ -93,18 +101,12 @@ Boolean
     }
 
 Sym
-    = id:$(SymV1) {
+    = id:$((Alpha / SymChars) (AlphaNum / SymChars)*) {
         return {type: NodeType.SYM, id};
     }
 
-SymV1
-    = (Alpha / SymChars) (AlphaNum / SymChars / [.])*
-
-SymV2
-    = Digit (AlphaNum / SymChars)+
-
 SymChars
-    = [*?$%&/\|~<>=_+\-]
+    = [*?$%&/\|~<>=_.+\-]
 
 Var
     = VarDeref