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import { callFn, emptyStackFrame, evaluate, lex, parse } from "../js-lang";
import {
Evaluate,
FnPrim,
Lex,
Parse,
EvalError,
CallFn,
EmptyStackFrame,
ASTNode,
StackFrame,
} from "../ts-lang";
export type TransformArgs<Args extends readonly ASTNode[]> = {
[Idx in keyof Args]: any;
};
export type AssertArgs<
Args extends readonly ASTNode[],
ArgsConstraint extends readonly any[]
> = TransformArgs<Args> extends ArgsConstraint ? ArgsConstraint : never;
export const createFn =
<ArgsConstraint extends any[]>() =>
<Program extends string>(
program: Program
): Evaluate<Parse<Lex<Program>>> extends infer E
? E extends [infer ProgramFn extends FnPrim]
? TransformArgs<ProgramFn["args"]> extends ArgsConstraint
? <const Args extends ArgsConstraint>(
...args: Args
) => CallFn<ProgramFn, Args, EmptyStackFrame, []>
: EvalError<`Program's args do not extend args constraint`>
: E extends readonly [
readonly [infer Prim extends FnPrim, infer StackFrame, infer Name]
]
? TransformArgs<Prim["args"]> extends ArgsConstraint
? <const Args extends ArgsConstraint>(
...args: Args
) => CallFn<E[0], Args, EmptyStackFrame, []>
: EvalError<`Program's args do not extend args constraint`>
: EvalError<"Cannot create a function from a program that does not eval to a function">
: never => {
const [e] = evaluate(parse(lex(program))) as [
FnPrim | [FnPrim, StackFrame, ASTNode["name"]]
];
const fn: FnPrim = Array.isArray(e) ? e[0] : e;
if (!fn.fn) {
throw new Error(
"Cannot create a function from a program that does not eval to a function"
);
}
return ((...args: any[]) => callFn(e, args, emptyStackFrame)) as any;
};
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