TypeScript · Senior · Question 52 of 75

What does tail-recursion elimination for conditional types (TS 4.5) allow?

✓Correct answer: Recursive conditional types in tail position can recurse much deeper (about 1000 levels) without "excessively deep" errors
2Unlimited recursion in all types
3Recursion in runtime functions

Explanation

Write recursive types with an accumulator so the recursive call is the whole branch result, e.g. Trim<Rest, [...Acc, X]>.

Further reading

TS 4.5: Tail-recursion elimination on conditional types ↗

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