diff options
Diffstat (limited to 'src/utils.ts')
| -rw-r--r-- | src/utils.ts | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/src/utils.ts b/src/utils.ts index 8e3abb9..15d5fb0 100644 --- a/src/utils.ts +++ b/src/utils.ts @@ -3,10 +3,13 @@ export const eq = (b: T): boolean => a === b +type TagValue<T, N> = T extends Tag<N, infer V> ? V : never; + export const match = - <R, K extends string>(pattern: { [key in K | '_']: () => R }) => - (k: K): R => - (pattern[k] || pattern._)() + <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] |