fix(pipeP): first fn should return PromiseLike

[ikatyang]

Fixes #361

[KiaraGrouwstra]

Hm. Wasn't R.pipeP(R.inc)(Promise.resolve(1)) valid Ramda as well? It seems this would forbid such usage. I feel that's important in the sense it means it's agnostic toward whether you wanna use it with synchronous or asynchronous functions, which makes it fairly flexible.

[antogyn]

One solution to this would be to make both valid, e.g. have both

declare function $<V1, R1>(fn1: (v1: V1) => PromiseLike<R1>): (v1: V1) => PromiseLike<R1>;

and

declare function $<V1, R1>(fn1: (v1: V1) => PromiseLike<R1> | R1): (v1: PromiseLike<V1>) => PromiseLike<R1>;

EDIT :

Actually, R.pipeP(R.inc)(Promise.resolve(1)) is not valid Ramda because the promise is directly passed to the first function, so in this case it returns NaN (and it breaks if you try R.pipeP(R.inc, R.inc)(Promise.resolve(1)) for example).

So I'd say that the typings in this PR are accurate.

[ikatyang]

As @antogyn mentioned, R.pipeP(R.inc)(Promise.resolve(1)) is not a valid Ramda since arguments are passed directly to the first function, which cause the result to be NaN (Promise.resolve(1) + 1), so I think this PR should be fine?

[KiaraGrouwstra]

Okay, think that worked before, but fair enough!