1 files changed, 7 insertions, 9 deletions
diff --git a/src/lib/core/eval.ts b/src/lib/core/eval.ts
index 10cc23c..74801bf 100644
--- a/src/lib/core/eval.ts
+++ b/src/lib/core/eval.ts
@@ -26,6 +26,10 @@ export type UnarrayIfOnlyHead<T extends readonly any[]> = T extends [
   ? Head
   : T;
 
+export type BUILTIN_ARR<Args extends readonly ASTNode[]> = {
+  [Idx in keyof Args]: Args[Idx] extends ASTNode ? Evaluate<Args[Idx]> : never;
+};
+
 export type BUILTIN_ToString<Args extends readonly ASTNode[]> = ToStringInner<
   UnarrayIfOnlyHead<{
     [Idx in keyof Args]: Args[Idx] extends ASTNode
@@ -38,25 +42,19 @@ export type BUILTIN_ToString<Args extends readonly ASTNode[]> = ToStringInner<
 export type SENTINEL_NO_BUILTIN = "__NO_BUILTIN__";
 export type MapBuiltins<Node extends ASTNode> = Node["name"] extends "tostring"
   ? BUILTIN_ToString<Node["children"]>
+  : Node["name"] extends "arr"
+  ? BUILTIN_ARR<Node["children"]>
   : SENTINEL_NO_BUILTIN;
 
 export type EvalError<T extends string> = `Eval error: ${T}`;
 
 export type Evaluate<Node extends ASTNode> = Node["type"] extends NodeType.INT
   ? Node["value"]
-  : Node["type"] extends NodeType.ROOT
-  ? Node["children"] extends infer Children extends readonly ASTNode[]
-    ? UnarrayIfOnlyHead<{
-        [Idx in keyof Children]: Children[Idx] extends ASTNode
-          ? Evaluate<Children[Idx]>
-          : never;
-      }>
-    : EvalError<`Unexpected error parsing children of ${Node["type"]}`>
   : Node["type"] extends NodeType.EXT
   ? MapBuiltins<Node>
   : EvalError<`Unhandled node type ${Node["type"]}`>;
 
-const input = `tostring(5, 2)` as const;
+const input = `5, arr(5000)` as const;
 const lex_result = null as unknown as Lex<typeof input>;
 const parse_result = null as unknown as Parse<typeof lex_result>;
 const eval_result = null as unknown as Evaluate<typeof parse_result>;