arktype•4mo ago

Record with number as key?

const A = type("Record<number, string>");

const A = type("Record<number, string>");

This throws error:

Argument of type '"Record<number, string>"' is not assignable to parameter of type '"K must be assignable to string | symbol (was number) "'

Argument of type '"Record<number, string>"' is not assignable to parameter of type '"K must be assignable to string | symbol (was number) "'

But it should be valid:

type A = Record<number, string>;

type A = Record<number, string>;

4 Replies

SynthLuvrOP•4mo ago

Also:

const B = ark.Record("number", "number");

const B = ark.Record("number", "number");

Argument of type '["number", "number"]' is not assignable to parameter of type '["number", "number"] & [ErrorType<"Invalid argument for K", [expected: Key]>, unknown]'.
  Type '["number", "number"]' is not assignable to type '[ErrorType<"Invalid argument for K", [expected: Key]>, unknown]'.
    Type at position 0 in source is not compatible with type at position 0 in target.
      Type 'string' is not assignable to type 'ErrorType<"Invalid argument for K", [expected: Key]>'

Argument of type '["number", "number"]' is not assignable to parameter of type '["number", "number"] & [ErrorType<"Invalid argument for K", [expected: Key]>, unknown]'.
  Type '["number", "number"]' is not assignable to type '[ErrorType<"Invalid argument for K", [expected: Key]>, unknown]'.
    Type at position 0 in source is not compatible with type at position 0 in target.
      Type 'string' is not assignable to type 'ErrorType<"Invalid argument for K", [expected: Key]>'

TizzySaurus•4mo ago

It's not possible to have numbers as a key in JS

TizzySaurus•4mo ago

Numbers are implicitly converted to strings

ssalbdivad•4mo ago

You could do Record<string.numeric, string> But yeah it was a big mistake for TS to include numeric keys that don't reflect a real language feature so that's an area where I'm consciously diverging

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Record with number as key?