25 lines
1.6 KiB
TypeScript
25 lines
1.6 KiB
TypeScript
//// [functionExpressionContextualTyping2.ts]
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// A contextual signature S is extracted from a function type T as follows:
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// If T is a function type with exactly one call signature, and if that call signature is non- generic, S is that signature.
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// If T is a union type, let U be the set of element types in T that have call signatures.
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// If each type in U has exactly one call signature and that call signature is non- generic,
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// and if all of the signatures are identical ignoring return types, then S is a signature
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// with the same parameters and a union of the return types.
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// Otherwise, no contextual signature can be extracted from T and S is undefined.
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var a0: (n: number, s: string) => number
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var a1: typeof a0 | ((n: number, s: string) => string);
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a1 = (foo, bar) => { return true; } // Error
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//// [functionExpressionContextualTyping2.js]
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// A contextual signature S is extracted from a function type T as follows:
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// If T is a function type with exactly one call signature, and if that call signature is non- generic, S is that signature.
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// If T is a union type, let U be the set of element types in T that have call signatures.
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// If each type in U has exactly one call signature and that call signature is non- generic,
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// and if all of the signatures are identical ignoring return types, then S is a signature
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// with the same parameters and a union of the return types.
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// Otherwise, no contextual signature can be extracted from T and S is undefined.
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var a0;
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var a1;
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a1 = function (foo, bar) { return true; }; // Error
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