A few canonicals and pseudo-canonicals for haskell:

Why shouldn't I mix tabs and spaces?

Function definiton by special cases in GHCi

Why doesn't this function work if I use “[xs]” instead of “xs”?

Why can String not be used in a constraint?

How to comfortably deal with the type system on Haskell?

Haskell GHC: what is the time complexity of a pattern match with N constructors?

the seq function and strictness

List manipulation performance in Haskell

Under what circumstances could Common Subexpression Elimination affect the laziness of a Haskell program?

Does Haskell have tail-recursive optimization?

Confused by the meaning of the 'Alternative' type class and its relationship to other type classes

Existential vs. Universally quantified types in Haskell

'type family' vs 'data family', in brief?

What is pipes/conduit trying to solve

How and why does the Haskell Cont monad work?

What is the difference between Cabal and Stack?