在打字稿中，如何从柯里化函数中第二个函数调用的参数类型推断参数类型

Question

if i have a function

const g = f => p => f(p)
g(x => x + 3)(5)

How do I type 'g' so that the type of x can be inferred from the argument '5'?

Answer 1

In the way you are describing it, it's impossible as your factory g might creat different functions as const func = g(x => x + 3); may be used as func('asdad') // returns 'asdad3' and func(5) // returns 8 . You cannot infer the type from usage this way as there are endless possibilities of usage. You have to apriori set the type of the x thus deciding whether it's gonna be func('asda') or func(5) .