Haskell: Difference between the function composition function (.) and operator $

http://learnyouahaskell.com/higher-order-functions#function-application

http://lambda.jstolarek.com/2012/03/function-composition-and-dollar-operator-in-haskell/

其实这有关操作符的优先级(priority)和关联性(association) (这里用了"操作符"这个名称，但是其实Haskell里全是函数。。。)

微妙之差(至少在表面上看来), 不可不察.

:)