add createFn

1 files changed, 27 insertions, 0 deletions

diff --git a/src/lang/ks-lang/index.ts b/src/lang/ks-lang/index.ts
new file mode 100644
index 0000000..c60203f
--- /dev/null
+++ b/src/lang/ks-lang/index.ts
@@ -0,0 +1,27 @@
+import { callFn, emptyStackFrame, evaluate, lex, parse } from "../js-lang";
+import {
+  Evaluate,
+  FnPrim,
+  Lex,
+  Parse,
+  EvalError,
+  CallFn,
+  EmptyStackFrame,
+} from "../ts-lang";
+
+export const createFn = <Program extends string>(
+  program: Program
+): Evaluate<Parse<Lex<Program>>> extends [infer ProgramFn extends FnPrim]
+  ? <const Args extends any[]>(
+      ...args: Args
+    ) => CallFn<ProgramFn, Args, EmptyStackFrame>
+  : EvalError<"Cannot create a function from a program that does not eval to a function"> => {
+  const [programFn] = evaluate(parse(lex(program))) as Array<FnPrim>;
+  if (!programFn.fn) {
+    throw new Error(
+      "Cannot create a function from a program that does not eval to a function"
+    );
+  }
+
+  return ((...args: any[]) => callFn(programFn, args, emptyStackFrame)) as any;
+};