typescript / expert
Snippet
Type-Safe Variadic Tuple Composition for Generic Pipeline Inferencing
This expert snippet uses recursive variadic tuple type unwrapping to validate end-to-end type safety in function pipelines. It recursively checks if function output B matches function input B for all steps at compile time.
snippet.ts
typescript
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type FlowChain<Fns extends any[]> = Fns extends [infer F1, infer F2, ...infer Rest]? F1 extends (arg: infer A) => infer B? F2 extends (arg: B) => any? FlowChain<[(arg: A) => F2 extends (arg: any) => infer C ? C : never, ...Rest]>: never: never: Fns extends [(arg: infer A) => infer B]? (arg: A) => B: never;type Pipeline = FlowChain<[(x: number) => string,(s: string) => string[],(arr: string[]) => number]>;
Breakdown
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type FlowChain<Fns extends any[]> = Fns extends [infer F1, infer F2, ...infer Rest]
Destructures the function array into first step (F1), second step (F2), and remaining functions (Rest).
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? F1 extends (arg: infer A) => infer B
Extracts argument type A and return type B from the first function signature using conditional type inference.
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? F2 extends (arg: B) => any
Verifies that the second function accepts type B as input; otherwise evaluates to never.