Sometimes we need read some articles, forums, blogs to understand Haskell features. But if we want just remind ourselves something we already knew, then is better just look at code sample. You could easily change it and play with it and see what's going on.
There are samples of Haskell code that explains how to use some its features.
This code is supposed to be isolated as much as possible - like if we wish to explain/remember one feature of Haskell then we are not going to use 5 more extra features for that (which might not be gotten yet by a reader of this code).
Each example has no more than 100 lines of code. Also there is tagging is used in order to show to the reader what feature is involved for particular example. Like #feature-1 #feature-3.
"Use the course, Luke!" (R)
For now for each example you may use GHCi - http://www.haskell.org/haskellwiki/GHC/GHCi
cd src
Prelude> :load 01_basics.hs
Prelude> y 8
Every time when you change code, type ":reload":
Prelude> :reload
etc.
So you can play with each example and see its values.