[Haskell-beginners] explaining effects

[Imants Cekusins]

for some practical purposes, would it make sense to forget about
effects and purity and distinguish only between IO and non-IO? It
should be easy enough to tell IO from non-IO, no?

also, could we say that a function that returns a value of such a type
of which no part is a function (for lack of a better definition) is
definitely a pure function

?