feat: adds simple evaluator

1 files changed, 14 insertions, 0 deletions

diff --git a/src/utils/result.ts b/src/utils/result.ts
new file mode 100644
index 0000000..c0120b8
--- /dev/null
+++ b/src/utils/result.ts
@@ -0,0 +1,14 @@
+import { Enum, constructors, match } from "./adt";
+
+export type Result<V, E> = Enum<{ Ok: V, Err: E }>
+export const Result = constructors<Result<any, any>>()
+
+export const mapResult = <A, B, E>(res: Result<A, E>, fn: (_: A) => B): Result<B, E> =>
+  chainResult(res, a => Result.Ok(fn(a)))
+
+export const chainResult = <A, B, E>(res: Result<A, E>, fn: (_: A) => Result<B, E>): Result<B, E> =>
+  match(res, {
+    Ok: a => fn(a),
+    Err: e => Result.Err(e),
+  });
+