在解析Happy Haskell时显示自定义错误 [英] Show custom errors while parsing Happy Haskell

问题描述

我的错误函数是这样定义的：

  parseError :: Token  - > Alex a 
 parseError _ = alexError发生错误
  

如何发送自定义错误（像尝试向数字中添加字符串时的类型不正确）？

---

更新

解析器不需要进行类型检查，因为我跟踪了操作数的类型，所以我在生产中进行了检查。
正如评论中所说，我不能使用 parseError ，所以有没有办法打印错误并停止解析器？

解决方案

我已经通过实现这个函数解决了它：

  fatalError ::（Show a1，Show a）=> [Char]  - > a  - > a1  - > t 
 fatalError slc = error（Error at line++（show l）++column++（show c）++：++ s）
  

我在检测到错误时从产品中调用它

I'm writing a monadic parser using Alex and Happy in Haskell.

My error function is defined like this:

parseError :: Token -> Alex a
parseError _ = alexError "error occurred"

How can I send custom errors (like incorrect type while trying to add a string to a number) during parsing?

---

UPDATE

The parser doesn't need to do the type checking, I'm doing it inside the production since I keep track of the operands type. As said in a comment, I cannot use the parseError, so is there a way to print an error and stop the parser?

解决方案

I've solved it by implementing this function:

fatalError :: (Show a1, Show a) => [Char] -> a -> a1 -> t
fatalError s l c = error ("Error at line " ++ (show l) ++ " column " ++ (show c) ++ ": " ++ s)

and I call it from the production when an error is detected

这篇关于在解析Happy Haskell时显示自定义错误的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！