Add vararg (.)

[Martoon-00]

Maybe introduce some (.:), where f .: g applies f to result of g, g accepts several arguments and returns monadic action?
For example lift .: seems to be handy

[neongreen]

I'm in favor of it.

[neongreen]

(Though I suspect type inference might not be so good, even for monadic actions. It'll likely get complicated by the fact that (->) is a monad as well – so, e.g. lift .: forever might not work.)

[neongreen]

Actually, maybe you should first check locally whether you even can write a (.:) that would work for your purposes.

[neongreen]

(A possible candidate for an implementation: http://okmij.org/ftp/Haskell/polyvar-comp.lhs. There might be others.)

[Martoon-00]

Oh really, I didn't provide that m a and r -> a would overlap.
Will try implementation at your your link, thanks

[chshersh]

I don't like vararg (.). You can't say from code how many arguments it takes. It will become difficult to understand and maintain code. And you can have cryptic error messages. I better propose to add family of composition functions to specify number of arguments explicitly:
http://hackage.haskell.org/package/composition-1.0.2.1/docs/Data-Composition.html

I've already proposed to add such functions under origin issue. But @gromakovsky shared his concerns regarding performance degrade.
https://issues.serokell.io/issue/SRK-10#comment=96-242

[chshersh]

Unfortunately, (.:) conflictis with aeson. So we should invent either our own syntax for multiple versions of (.), (.:), (.:.), (.::), etc. or do something else. But I really like those composition operators.

[chshersh]

Implemented in this commit: 8c26301
I like it. I think issue can be closed.