これも面白そうなのでメモ

http://www.haskell.org/hawiki/ThingsToAvoid
"Choose the right fold"ってのが、いまいちよくわからねぇ。

So, we arrive at the one-line summary: A function strict in its second argument will always* require linear stack space with foldr, so foldl' should be used instead in that case. If the function is lazy/non-strict in its second argument we should use foldr to 1) support infinite lists and 2) to allow a streaming use of the input list where only part of it needs to be in memory at a time.

を言いたいだけなのか？
そして、Concurrent Cleanの場合には、この格言はどういうふうに翻訳すればいいのか？