desugaring for let/def expressions, more error handling, expanded test cases

desugar.js

@@ -20,11 +20,16 @@ function desugarList(lst) {
 }
 
 function desugarDefFunc(def) {
-  return new typ.Def(def.ident, new typ.FuncT(desugar(def.params), desugar(def.body)));
+  return new typ.Def(def.ident,
+                     new typ.FuncT(desugar(def.params),
+                                   desugar(def.body)));
 }
 
-//function desugarString(str) {
 
+function desugarLet(stx) {
+  var values = stx.pairs.map(desugar);
+  return new typ.LetExp(values, desugar(stx.body));
+}
 
 function desugar(stx) {
   switch (stx.exprType) {
@@ -59,6 +64,8 @@ function desugar(stx) {
       return stx;
     case "Integer":
       return stx;
+    case "Let":
+      return desugarLet(stx);
     default:
       return stx;
   }

parse.js

@@ -188,8 +188,8 @@ function parseLetForm(tokens, linenum, charnum) {
                              charnum,
                              "Unexpected end of source");
   }
-  linenum = fst(tokens)[2];
-  charnum = fst(tokens)[3];
+  linenum = fst(tokens)[3];
+  charnum = fst(tokens)[2];
   tokens.pop();
   if (tokens.length <= 0) {
     throw error.JSyntaxError(linenum,
@@ -197,6 +197,12 @@ function parseLetForm(tokens, linenum, charnum) {
                              "let/def form must have a body");
   }
   var body = parse(tokens);
+  if (body.exprType === "Definition" ||
+      body.exprType === "FunctionDefinition") {
+        throw error.JSyntaxError(linenum,
+                                 charnum,
+                                 "Body of a let/def expression cannot be a definition");
+      }
   return new typ.LetExp(pairs, body);
 
 }
@@ -250,14 +256,21 @@ function parseLetBinding(tokens, linenum, charnum) {
   }
   tokens.pop();
   if (!notFollowedBy(tokens,
-                       ["def", "comma", "arrow", "right_brace", "right_square"],
+                       ["comma", "arrow", "right_brace", "right_square"],
                        linenum,
                        charnum)) {
       throw error.JSyntaxError(linenum,
                                charnum,
                                "The binding of " + identifier.val + " must not be followed by " + fst(tokens)[0]);
                        }
-	return new typ.Def(name, parse(tokens));
+  var bound = parse(tokens);
+  if (bound.exprType === "Definition" ||
+      bound.exprType === "FunctionDefinition") {
+        throw error.JSyntaxError(linenum,
+                                 charnum,
+                                 "A definition cannot be the value of a binding");
+      }
+	return new typ.Def(name, bound);
 }
 
 function parseLetItem(tokens) {
@@ -289,8 +302,8 @@ function parseDef(tokens, linenum, charnum) {
     /* It's a let/def form */
     tokens.pop();
     return parseLetForm(tokens,
-                        fst(tokens)[2],
-                        fst(tokens)[3]);
+                        fst(tokens)[3],
+                        fst(tokens)[2]);
   }
 
 	if (notFollowedBy(tokens, ["identifier"], linenum, charnum)) {
@@ -307,14 +320,21 @@ function parseDef(tokens, linenum, charnum) {
     linenum = fst(tokens)[3];
     charnum = fst(tokens)[2];
     if (!notFollowedBy(tokens,
-                       ["def", "comma", "arrow", "right_brace", "right_square"],
+                       ["comma", "arrow", "right_brace", "right_square"],
                        linenum,
                        charnum)) {
       throw error.JSyntaxError(linenum,
                                charnum,
                                "def " + identifier.val + " must not be followed by " + fst(tokens)[0]);
     }
-		return new typ.Def(identifier, parse(tokens));
+    var bound = parse(tokens);
+    if (bound.exprType === "Definition" ||
+      bound.exprType === "FunctionDefinition") {
+        throw error.JSyntaxError(linenum,
+                                 charnum,
+                                 "A definition cannot be the value of a binding");
+      }
+		return new typ.Def(identifier, bound);
 	}
  }
 
@@ -517,9 +537,9 @@ function parseFull(tokenized) {
       process.exit(1);
   }
 }
-//console.log(parseFull(tokenizer.tokenize(istr)).map(pprint.pprint).join("\n"));
+console.log(parseFull(tokenizer.tokenize(istr)).map(pprint.pprint).join("\n"));
 
 //console.log(tokenizer.tokenize(istr));
-console.log(parseFull(tokenizer.tokenize(istr)));
+//console.log(parseFull(tokenizer.tokenize(istr)));
 
 //module.exports = {parse : tool.compose(parseFull, tokenizer.tokenize) };

pprint.js

@@ -55,6 +55,11 @@ function pprint(expr) {
     return "[]";
   else if (expr.exprType === "Unary")
     return "("+expr.op.ident+" "+pprint(expr.val)+")";
+  else if (expr.exprType === "Let")
+    return "let {" + expr.pairs.map(
+          function (v) {
+            return pprint(v)
+          }).join(" ; ") + "} in " + pprint(expr.body);
 }
 
 module.exports = {pprint : pprint};

representation.js

@@ -215,4 +215,5 @@ module.exports =
    DefFunc : DefFunc,
    UnaryOp : UnaryOp,
    Nil : Nil,
-   LetExp : LetExp}
+   LetExp : LetExp
+   }

test.jl

@@ -44,12 +44,22 @@ def (splitHelp acc xs ys)
 def (splitxs xs)
   (splitHelp [] xs xs)
 
+def r def
+  {
+    a = 4
+  }
+    a
+
 def main
-  ((print (testUnary 6)) >>
-  if False
-    then
-      undefined
-    else fileLines
-    >>
-    (print
-      (splitxs [12,3,4,56])))
+  let {
+    unary = (print (testUnary 6))
+    splitted = def {
+                xs = (fst (splitxs [12,3,4,56]))
+                } (xs ++ [0,9])
+    }
+      if False
+        then undefined
+      else
+        (unary >>
+         fileLines >>
+         (print splitted))