小编use*_*181的帖子

if even 2 then 10 else 11 -- works fine

if even 2 then let t = 10 else let s = 11 -- _:27: parse error on input 'else'

if even 2 then 10 else let s = 11 -- _:34 parse error (possibly incorrect indentation or mismatched brackets)

因为假设我想用 [[p]] 编写这样的代码：

[ t | let e = [], 
      let o = p!!14, r <- [13,12..1], 
      if even r 
      then 
         let o = zipWith (+) (p!!r) (zipWith max e …