A small peeve

Whenever I write a function with an external wrapper and an internal recursive function (say, to add an accumulator), I can never come up with a name for the internal function that I find satisfying. This is totally picking nits, but it bugs me for all the recursive calls to be to foo/aux or foo/helper or something like that. Come to think of it, somehow the prime symbol in Haskell and ML feels more natural.

Well said

From the GHC wiki:

It's much better to write code that is transparent than to write code that is short.

Often it's better to write out the code longhand than to reuse a generic abstraction (not always, of course). Sometimes it's better to duplicate some similar code than to try to construct an elaborate generalisation with only two instances. Remember: other people have to be able to quickly understand what you've done, and overuse of abstractions just serves to obscure the really tricky stuff.