Haskell在`ghci`中多行`let`(Haskell multi-line `let` in `ghci`)

 我在ghci ，发现以下工作： 
 
let foo = ["a", "b", "c"]
 
 ......但这不起作用： 
 
let bar = ["a",
           "b",
           "c"]
 
 ......也不是这样的： 
 
let baz = ["a"] ++
          ["b"] ++
          ["c"]
 
 当我尝试将其编译为文件时，提供了相同的错误，因此它不是来自ghci与使用ghc 。 
 
 错误： 
 
[1 of 1] Compiling Main             ( test.hs, test.o )

test.hs:3:1: error:
    parse error (possibly incorrect indentation or mismatched brackets)

I'm in ghci and find that the following works:
 
let foo = ["a", "b", "c"]
 
... but this doesn't work:
 
let bar = ["a",
           "b",
           "c"]
 
... nor does this:
 
let baz = ["a"] ++
          ["b"] ++
          ["c"]
 
The same error is provided when I try to compile it as a file, so it's not something that comes from being in ghci vs using ghc.
 
The error:
 
[1 of 1] Compiling Main             ( test.hs, test.o )

test.hs:3:1: error:
    parse error (possibly incorrect indentation or mismatched brackets)

原文：https://stackoverflow.com/questions/40933256