refactor: creates constructors for expr adt

1 files changed, 15 insertions, 0 deletions

diff --git a/src/utils.ts b/src/utils.ts
index 9c4c97b..6591050 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -7,3 +7,18 @@ export const match =
   <R, K extends string>(pattern: { [key in K | '_']: () => R }) =>
   (k: K): R =>
     (pattern[k] || pattern._)()
+
+type Tag<N, V> = { tag: N; value: V }
+export type Union<T> = { [N in keyof T]: Tag<N, T[N]> }[keyof T]
+
+export const constructors = <T extends Record<string, any>>(): {
+  [N in keyof T]: (value: T[N]) => Union<T> // Tag<N, T[N]>
+} =>
+  new Proxy(
+    {},
+    {
+      get(_, k) {
+        return (value: any) => ({ tag: k, value })
+      },
+    }
+  ) as any