Haskell优先级：Lambda和运算符

Question

我发现优先级和关联性是一个很大的障碍，让我理解语法在haskell代码中试图表达的内容。

例如，

blockyPlain :: Monad m => m t -> m t1 -> m (t, t1)
blockyPlain xs ys = xs >>= \x -> ys >>= \y -> return (x, y)

通过实验，我终于明白了，

blockyPlain xs ys = xs >>= (\x -> (ys >>= (\y -> return (x, y))))

blockyPlain xs ys = xs >>= (\x -> ys) >>= (\y -> return (x, y))

*Main> blockyPlain [1,2,3] [4,5,6]
[(1,4),(1,5),(1,6),(2,4),(2,5),(2,6),(3,4),(3,5),(3,6)]

你们谁能提供一些参考，让语法更容易掌握吗？

Answer 1

lambda的规则非常简单：lambda的主体尽可能向右延伸，而不会碰到不平衡的括号。

f (\x -> foo (bar baz) *** quux >>= quuxbar)
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
                       body