Hi,

Am Freitag, den 19.08.2016, 11:16 -0700 schrieb Theodore Lief Gannon:
> Well... there's that rather worrisome introductory paragraph of the
> Data.Composition docs, though:
>
> "This module is for convenience and demonstrative purposes more than
> it is for providing actual value. I do not recommend that you rely on
> this module for performance-sensitive code. Because this module is
> not based on Prelude's (.), some chances at optimization might be
> missed by your compiler."

I wonder if that is really something to worry about. Prelude’s (.) is
not special in any way: 

The INLINE pragma and the definition with the right arity could be used
in Data.Composition as well, and it would yield the same results.