Change 'identity' to 'id' back

[chshersh]

This is more user friendly.

[gromakovsky]

Sometimes I even see import Data.Function (id).

[volhovm]

I'd leave both of them to preserve backward compatibility. The original point was "id is a good name for some variable", but as far as i see, it's a super rare usecase.

[johnchandlerburnham]

id :: a -> a is basically an idiom. If used as a variable, it's sort-of like an implicit overloading that might confuse people. There are other options for variable naming like idN or idT that are almost as good

[chshersh]

Let's export id but keep identity as well for compatibility.