Re-enable function expressions (#106)

* Revert "Disable function expressions (#96)"

This reverts commit 615fb51.

* Bump version

package.json

@@ -1,6 +1,6 @@
 {
   "name": "js-slang",
-  "version": "0.1.13",
+  "version": "0.1.14",
   "description": "Javascript-based interpreter for slang, written in Typescript",
   "author": {
     "name": "Source Academy",

src/__tests__/__snapshots__/disallowed_syntax.ts.snap

@@ -8,8 +8,4 @@ exports[`Cannot leave blank expressions in for loops 3`] = `"Line 2: For stateme
 
 exports[`Cannot leave blank expressions in for loops 4`] = `"Line 2: For statement cannot have empty init,test,update expressions."`;
 
-exports[`Cannot use js function expressions 1`] = `"Line 2: Function expressions are not allowed"`;
-
 exports[`Cannot use update expressions 1`] = `"Line 3: Update expressions are not allowed"`;
-
-exports[`DEFINITELY CANNOT use named function declarations as expressions 1`] = `"Line 2: Function expressions are not allowed"`;

src/__tests__/disallowed_syntax.ts

@@ -57,32 +57,3 @@ test("Cannot use update expressions", () => {
   });
 });
 
-test("Cannot use js function expressions", () => {
-  const code = `
-  map(function(x) {
-    return x + 1;
-  }, list(1));
-  `;
-  const context = mockContext(3);
-  const promise = runInContext(code, context, { scheduler: "preemptive" });
-  return promise.then(obj => {
-    expect(obj.status).toBe("error");
-    const errors = parseError(context.errors);
-    expect(errors).toMatchSnapshot();
-  });
-});
-
-test("DEFINITELY CANNOT use named function declarations as expressions", () => {
-  const code = `
-  map(function a(x) {
-    return x + 1;
-  }, list(1));
-  `;
-  const context = mockContext(3);
-  const promise = runInContext(code, context, { scheduler: "preemptive" });
-  return promise.then(obj => {
-    expect(obj.status).toBe("error");
-    const errors = parseError(context.errors);
-    expect(errors).toMatchSnapshot();
-  });
-});

src/interpreter.ts

@@ -175,6 +175,9 @@ export const evaluators: { [nodeType: string]: Evaluator<es.Node> } = {
     }
     return res
   },
+  FunctionExpression: function*(node: es.FunctionExpression, context: Context) {
+    return new Closure(node, currentFrame(context), context)
+  },
   ArrowFunctionExpression: function*(node: es.Function, context: Context) {
     return new ArrowClosure(node, currentFrame(context), context)
   },

src/syntaxTypes.ts

@@ -11,6 +11,7 @@ const syntaxTypes: { [nodeName: string]: number } = {
   BinaryExpression: 1,
   LogicalExpression: 1,
   ConditionalExpression: 1,
+  FunctionExpression: 1,
   ArrowFunctionExpression: 1,
   Identifier: 1,
   Literal: 1,
@@ -44,9 +45,7 @@ const syntaxTypes: { [nodeName: string]: number } = {
   CatchClause: Infinity,
   DoWhileStatement: Infinity,
   ForInStatement: Infinity,
-  SequenceExpression: Infinity,
-  FunctionExpression: Infinity,
-
+  SequenceExpression: Infinity
 }
 
 export default syntaxTypes