Fix Tail behaviour on issue #1

webNeat · Mar 21, 2022 · f438878 · f438878
1 parent ab9d807
commit f438878
Showing 1 changed file with 6 additions and 1 deletion.
diff --git a/src/Tail.ts b/src/Tail.ts
@@ -1,10 +1,15 @@
 import {Equal, Is} from './Is'
 
-export type Tail<List extends any[]> = List extends [infer _, ...infer Rest] ? Rest : []
+export type Tail<List extends any[]> = ((...args: List) => any) extends (arg: any, ...rest: infer Rest) => any
+ ? Rest
+ : never
 
 type Tests = [
  Is<Equal<Tail<[]>, []>>,
  Is<Equal<Tail<['a']>, []>>,
  Is<Equal<Tail<['a', 'b']>, ['b']>>,
  Is<Equal<Tail<['a', 'b', 'c', 'd']>, ['b', 'c', 'd']>>
 ]
+type Test_Join<T extends string[]> = T extends [infer X, ...string[]]
+ ? `${X extends string ? X : ''}${Test_Join<Tail<T>>}`
+ : ''