3 files changed, 56 insertions, 25 deletions

diff --git a/src/lang/js-lang/builtin/builtin.ts b/src/lang/js-lang/builtin/builtin.ts
index ed279f6..bc40794 100644
--- a/src/lang/js-lang/builtin/builtin.ts
+++ b/src/lang/js-lang/builtin/builtin.ts
@@ -61,10 +61,12 @@ export const V_BUILTIN_Eq: BUILTIN = (args) => {
     }
 
     if (last === firstLast) {
+      last = arg;
       continue;
     }
 
     if (arg === last) {
+      last = arg;
       continue;
     }
 
@@ -74,20 +76,6 @@ export const V_BUILTIN_Eq: BUILTIN = (args) => {
   return true;
 };
 
-export const V_BUILTIN_IfElse: BUILTIN = (args) => {
-  if (args.length !== 3) {
-    throw new Error(`Invalid args for "if": ${JSON.stringify(args)}`);
-  }
-
-  const [cond, trueVal, falseVal] = args;
-
-  if (typeof cond !== "boolean") {
-    throw new Error(`Condition value ${JSON.stringify(cond)} is not a boolean`);
-  }
-
-  return cond ? trueVal : falseVal;
-};
-
 export const nameToBUILTIN: Record<string, BUILTIN> = {
   arr: V_BUILTIN_Arr,
   tostring: V_BUILTIN_ToString,
@@ -95,5 +83,4 @@ export const nameToBUILTIN: Record<string, BUILTIN> = {
   sub: V_BUILTIN_Sub,
   mul: V_BUILTIN_Mul,
   eq: V_BUILTIN_Eq,
-  "?": V_BUILTIN_IfElse,
 };
diff --git a/src/lang/js-lang/builtin/sbuiltin.ts b/src/lang/js-lang/builtin/sbuiltin.ts
index e5bc6ab..663c2f9 100644
--- a/src/lang/js-lang/builtin/sbuiltin.ts
+++ b/src/lang/js-lang/builtin/sbuiltin.ts
@@ -1,4 +1,4 @@
-import { callFn, getEvaluatedChildren } from "../core/eval";
+import { _evaluate, callFn, getEvaluatedChildren } from "../core/eval";
 import { ASTNode, FnPrim, StackFrame } from "../../ts-lang";
 
 type SBUILTIN = (node: ASTNode, frame: StackFrame) => any;
@@ -40,7 +40,24 @@ export const V_SBUILTIN_Map: SBUILTIN = (node, frame) => {
   return values.map((v, i) => callFn(fn, [v, i], frame));
 };
 
+export const V_SBUILTIN_IfElse: SBUILTIN = (node, frame) => {
+  const children = node.children;
+
+  if (children.length !== 3) {
+    throw new Error(`Invalid args for "if": ${JSON.stringify(children)}`);
+  }
+
+  const cond = _evaluate(children[0], frame);
+
+  if (typeof cond !== "boolean") {
+    throw new Error(`Condition value ${JSON.stringify(cond)} is not a boolean`);
+  }
+
+  return cond ? _evaluate(children[1], frame) : _evaluate(children[2], frame);
+};
+
 export const nameToSBUILTIN: Record<string, SBUILTIN> = {
   call: V_SBUILTIN_Call,
   map: V_SBUILTIN_Map,
+  "?": V_SBUILTIN_IfElse,
 };
diff --git a/src/lang/js-lang/core/eval.ts b/src/lang/js-lang/core/eval.ts
index 60a2059..1a9e292 100644
--- a/src/lang/js-lang/core/eval.ts
+++ b/src/lang/js-lang/core/eval.ts
@@ -6,6 +6,7 @@ import {
   NodeType,
   FnPrim,
   SENTINEL_NO_BUILTIN,
+  NamedFnPrim,
 } from "../../ts-lang";
 import { nameToBUILTIN, nameToSBUILTIN, V_SBUILTIN_Map } from "../builtin";
 
@@ -27,11 +28,24 @@ const findInStack = (frame: StackFrame, nameToFind: string) => {
     return frame.bindings[nameToFind];
   }
 
-  if (!frame.parent) {
-    throw new Error(`Can't find name ${nameToFind} on the stack`);
+  throw new Error(`Can't find name ${nameToFind} on the stack`);
+};
+
+const handleBind = (node: ASTNode, frame: StackFrame) => {
+  const inner = _evaluate(node.children[1], frame);
+
+  if (inner.fn) {
+    const named: NamedFnPrim<any, any, any, any> = {
+      args: inner.args,
+      fn: inner.fn,
+      name: node.children[0].name,
+      frame,
+    };
+
+    return named;
   }
 
-  return findInStack(frame.parent, nameToFind);
+  return inner;
 };
 
 const handleFn = (node: ASTNode): FnPrim => {
@@ -46,13 +60,22 @@ const handleFn = (node: ASTNode): FnPrim => {
 const mapZip = (args: ASTNode[], values: any[]) =>
   Object.fromEntries(args.map(({ name }, i) => [name, values[i]]));
 
-export const callFn = (fn: FnPrim, values: any[], frame: StackFrame) =>
-  _evaluate(fn.fn, {
-    bindings: mapZip(fn.args as ASTNode[], values),
-    parent: frame,
+export const callFn = (fn: FnPrim, values: any[], frame: StackFrame) => {
+  if ((fn as NamedFnPrim<any, any, any, any>).frame) {
+    return _evaluate(fn.fn, {
+      bindings: {
+        ...mapZip(fn.args as ASTNode[], values),
+        ...frame.bindings,
+        ...(fn as NamedFnPrim<any, any, any, any>).frame.bindings,
+      },
+    });
+  }
+  return _evaluate(fn.fn, {
+    bindings: { ...mapZip(fn.args as ASTNode[], values), ...frame.bindings },
   });
+};
 
-export const _evaluate = (node: ASTNode, frame: StackFrame) => {
+export const _evaluate = (node: ASTNode, frame: StackFrame): any => {
   if (node.type === NodeType.INT) {
     return node.value;
   }
@@ -62,6 +85,10 @@ export const _evaluate = (node: ASTNode, frame: StackFrame) => {
       return handleFn(node);
     }
 
+    if (node.name === "bind") {
+      return handleBind(node, frame);
+    }
+
     const builtinResult = mapBuiltins(node, frame);
     if (builtinResult !== V_SENTINEL_NO_BUILTIN) {
       return builtinResult;
@@ -76,7 +103,7 @@ export const _evaluate = (node: ASTNode, frame: StackFrame) => {
 export const getEvaluatedChildren = (node: ASTNode, frame: StackFrame) =>
   node.children.map((child) => _evaluate(child, frame));
 
-export const emptyStackFrame: EmptyStackFrame = { bindings: {}, parent: null };
+export const emptyStackFrame: EmptyStackFrame = { bindings: {} };
 
 export const evaluate = <const Node extends ASTNode>(
   node: Node