Re: [Haskell-cafe] How is this variable not in scope?

Another solution is to define `f` below `root` within the do block: ``` main' = do (root : inputFile :_) <- getArgs input <- readFile inputFile let pairs = pairFilesToContents $ readSmsnLines input let f :: (FilePath, String) -> IO () f (name, content) = writeFile (root+name) content mapM_ f pairs ``` On Fri, 21 Jul 2017 at 10:07 Jeffrey Brown wrote:

Excellent! Thanks, Alejandro!

On Fri, Jul 21, 2017 at 12:52 AM, Alejandro Serrano Mena < trupill@gmail.com> wrote:

...

The problem is that in the "where" clause the only things which are in scope are (roughly) the arguments of the function. In particular, neither "root" nor "inputFile" nor "input" nor "pairs". The solution is to add an extra argument:

main' = do ... mapM_ (f root) pairs where f root (name, content) = writeFile (root ++ name) content

2017-07-21 9:28 GMT+02:00 Jeffrey Brown :

...

The following compiles and runs perfectly:

main = do (inputFile:_) <- getArgs input <- readFile inputFile let pairs = pairFilesToContents $ readSmsnLines input mapM_ f pairs where f :: (FilePath, String) -> IO () f (name, content) = writeFile name content

But the following triggers the error "Not in scope: ‘root’".

main' = do (root : inputFile :_) <- getArgs input <- readFile inputFile let pairs = pairFilesToContents $ readSmsnLines input mapM_ f pairs where f :: (FilePath, String) -> IO () f (name, content) = writeFile (root+name) content

-- Jeff Brown | Jeffrey Benjamin Brown Website https://msu.edu/~brown202/ | Facebook https://www.facebook.com/mejeff.younotjeff | LinkedIn https://www.linkedin.com/in/jeffreybenjaminbrown(spammy, so I often miss messages here) | Github https://github.com/jeffreybenjaminbrown

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-- Jeff Brown | Jeffrey Benjamin Brown Website https://msu.edu/~brown202/ | Facebook https://www.facebook.com/mejeff.younotjeff | LinkedIn https://www.linkedin.com/in/jeffreybenjaminbrown(spammy, so I often miss messages here) | Github https://github.com/jeffreybenjaminbrown

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