From 6b9a3d2ee4ec49f38f02106e3aa264946b7cdc93 Mon Sep 17 00:00:00 2001
From: Akshay Nair <phenax5@gmail.com>
Date: Thu, 13 Jan 2022 14:49:05 +0530
Subject: refactor: type + constructors refactor

---
 src/utils.ts | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

(limited to 'src/utils.ts')

diff --git a/src/utils.ts b/src/utils.ts
index 15d5fb0..66c4c53 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -3,19 +3,22 @@ export const eq =
   (b: T): boolean =>
     a === b
 
-type TagValue<T, N> = T extends Tag<N, infer V> ? V : never;
+type TagValue<T, N> = T extends Tag<N, infer V> ? V : never
 
 export const match =
-  <R, T extends Tag<string, any>>
-  (pattern: { [key in T['tag'] | '_']?: (v: TagValue<T, key>) => R }) =>
-    (tag: T): R =>
-      (pattern[tag.tag] || pattern._ as any)(tag.value)
+  <R, T extends Tag<string, any>>(pattern: {
+    [key in T['tag'] | '_']?: (v: TagValue<T, key>) => R
+  }) =>
+  (tag: T): R =>
+    (pattern[tag.tag] || (pattern._ as any))(tag.value)
 
 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]>
+export const constructors = <T extends Tag<string, any>>(): {
+  [N in T['tag']]: TagValue<T, N> extends null|never
+    ? (value?: null | never) => T
+    : (value: TagValue<T, N>) => T
 } =>
   new Proxy(
     {},
@@ -27,4 +30,3 @@ export const constructors = <T extends Record<string, any>>(): {
   ) as any
 
 export const jlog = (x: any) => console.log(JSON.stringify(x, null, 2))
-
-- 
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