在其中使用部分函数时分析错误（Haskell） [英] Parse errors when using partial functions in where statments (Haskell)

问题描述

我对Haskell很新，我遇到过几次这样的问题，并且没有在网上找到答案。

I'm pretty new to Haskell and I've run into this problem a few times and have had no luck finding answers online.

playDomsHandler (dp1,h1,s1) (dp2,h2,s2) b _
    -- players 1 and 2 both knocking, game ends
    | knockingP b h1 && knockingP b h2 = (b, (s1, s2))
    -- just player 1 knocking, player 2 makes a move
    | knockingP b h1 = playDomsHandler (dp1,h1,s1) (dp2,h2,nScore2) nBoard2 2
    -- just player 2 knocking, player 1 makes a move
    | knockingP b h2 = playDomsHandler (dp1,h1,nScore1) (dp2,h2,s2) nBoard1 1
    where 
      (nBoard1, nScore1) = nextPlay (dp1,h1,s1) b
      (nBoard2, nScore2) = nextPlay (dp2,h2,s2) b

给出分析错误。 （（nBoard2，nScore2）行中的第一个括号）

Gives a parse error. (The first bracket in the (nBoard2, nScore2) line)

我以前使用过很多语句，但在使用部分函数时似乎总是遇到此问题

I've used where statements plenty before but I always seem to run into this problem when using partial functions

非常感谢任何帮助。

推荐答案

我打赌您使用的是制表符而不是空格来缩进。

I bet you are using tabs instead of white space for indentation.

结构中的陈述必须一致。 Haskell将解释每个标签，如8个空格，所以如果你正在搞乱空格和标签，可能你的函数没有对齐。

The statements in the where construction must be aligned. Haskell interprets every tabs like 8 white space, so if you are messing with white space and tabs maybe your functions are not aligned.

如果你的编辑器配置了选项卡， 4空白区域，你没有看到这个问题，但Haskell确实。

If your editor is configured with tabs showing to 4 white space, you are not seeing this problem, but Haskell does.

我将使用 - 作为空格和 \ t por选项卡（等于4个空格）。

I will use - for white space and \t por tabs (equal to 4 white space).

例如：

where 
----(nBoard1, nScore1) = nextPlay (dp1,h1,s1) b
\t  (nBoard2, nScore2) = nextPlay (dp2,h2,s2) b

这些不是对齐的，所以Haskell将在（nBoard2，nScore2）上给出解析错误

These are not aligned, so Haskell will give parse error on (nBoard2, nScore2)

我建议始终使用空格而不是制表符。大多数编辑器可以配置为替换4或8个空格字符的标签，所以你不会遇到这个问题。

I recomend to use always white space instead of tabs. Most editors can be configured to replace tabs with 4 or 8 white space characters, so you will not get this problem.

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