http://learnyouahaskell.com/higher-order-functions#function-applicationapp
http://lambda.jstolarek.com/2012/03/function-composition-and-dollar-operator-in-haskell/函數
其實這有關操做符的優先級(priority)和關聯性(association) (這裏用了"操做符"這個名稱,可是其實Haskell裏全是函數。。。)ci
微妙之差(至少在表面上看來), 不可不察.get
:)it