General documentation / cheat sheets for various languages and services

haskell

operators

$ constrains associativity. It kind of says "execute everything on the right first." E.g.: sum $ filter even [1..100] is equivalent to sum (filter even [1..100]).
<$> is the same as liftA{n}
<*> is the same as ApplicativeDo
^. is the same as view
^.. is the same as toListOf
%~ is the same as over
.~ is the same as set