标签: parse-error 在Haskell中解析错误 以下代码: import IO import System(getArgs) main = do args <- getArgs let l = length args if l == 0 putStrLn "foo" else putStrLn "bar" Run Code Online (Sandbox Code Playgroud) 为if-else子句生成解析错误.我尝试使用花括号无济于事.救命!haskell ...
Haskell no parse中的异常处理 检测Read解析器是否失败的最简单方法是使用readMaybe。例如,在GHCi中: > import Text.Read (readMaybe)> :t readMaybereadMaybe :: Read a => String -> Maybe a -- Defined in ‘Text.Read’> readMaybe "1" :: Maybe IntJust 1> readMaybe ":(" :: Maybe IntNothin...
The match method provides a poor-man's equivalent to Haskell's pattern-matching. It could be used, for example, to extract the result from a Reply:<A> A getResult(Reply<A> reply) { return reply.match( ok -> ok.result, error -> {throw new RuntimeException("Error");} ); }...
Haskell:IO程序中的解析错误 我正在写一个程序来帮助我的弟弟学习加法.我没有编写IO程序的经验,而且我遇到了这个解析错误: MyCode.hs:6:25: Parse error in pattern:showPossibly causedbyamissing'do'? Run Code Online (Sandbox Code Playgroud) 代码: ...
这是我的Haskell代码,当我尝试在GHCI解释器中运行此代码时,我收到以下错误: ascending.hs(File_name):4:13:Parseerrorinpattern:lengthFailed,modulesloaded:none. Run Code Online (Sandbox Code Playgroud) 谁能告诉我这个bug在哪里? haskellparse-error ...