Why does typescript require names in function types?

Question

Why do we need to name the parameter types in the type annotation of functions?

let f: (a:number, b:number) => number;

Why is a and b required here?

It's a design decision on the TS designers part. They are there for semantic documentation. — Titian Cernicova-Dragomir
– Titian Cernicova-Dragomir, Commented Aug 27, 2020 at 8:42
Becsuse a good variable naming is a key to an efficient and readable code. Without argument names you will have to provide an annotation for every parameter. Parameters like a and b make no sense for another developer, while haystack and needle are self-descriptive — Majesty
– Majesty, Commented Aug 27, 2020 at 8:43
Which one do you find more clear (string, string, number) => Person or (firstName: string, lastName: string, age: number) => Person? — VLAZ
– VLAZ, Commented Aug 27, 2020 at 8:49
Although I agree with those who say it is clearer to require names, it is worth pointing out that there would be a syntactic ambiguity if names were optional. — Aluan Haddad
– Aluan Haddad, Commented Aug 27, 2020 at 14:30

Zer0 · Accepted Answer · 2020-08-27 08:59:40Z

2

This is a design decision to make the code more readable. Also parameters in "normal" functions also need a name. Let's take the example of you using a libary which includes arrow functions, what do you think is easier to use of the following two examples?

const getResult: (string, number?, number?) => queryObject;

or

const getResult: (id: string, startIndex?: number, endIndex?: number) => queryObject;

I hope this makes it clear to you

answered Aug 27, 2020 at 8:59

Zer0

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