'mod'Haskell上的语法错误 [英] Syntax error on 'mod' Haskell

问题描述

我正在关注一个haskell教程： http：// www。 seas.upenn.edu/~cis194/lectures/01-intro.html

I am following a haskell tutorial: http://www.seas.upenn.edu/~cis194/lectures/01-intro.html

我正在测试ghci中的函数，我得到了这个部分：

I am testing functions in ghci, i got to this part:

hailstone :: Integer -> Integer
hailstone n
  | n `mod` 2 == 0 = n `div` 2
  | otherwise      = 3*n + 1

我在.hs文件中有这个功能，我启动了ghci在同一个目录中，并执行：l hailstone.hs

I have that function in a .hs file, i fire up ghci in the same directory and go :l hailstone.hs

输出是

the output is

Syntax error on 'mod'
    Perhaps you intended to use TemplateHaskell
    In the Template Haskell quotation 'mod'
Failed, modules loaded: none.

做了一些Google搜索，试图加载这个'templatehaskell'，结果出现了一组不同的错误（ http://brandon.si/code/working-with-template -haskell-in-ghci / ）

did some googling and tried to load this 'templatehaskell' and just ended up with a different set of errors (http://brandon.si/code/working-with-template-haskell-in-ghci/)

推荐答案

user2407038 正确地建议在评论中，问题是我使用撇号（'）而不是反引号（`），反引号与我应该使用的单引号不一样。

As user2407038 correctly suggested in the comments, the problem was that I was using apostrophes (') as opposed to backticks (`), the backtick is not the same as the single quote which I should have been using.

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