On Aug 17, 2007, at 9:11 , rodrigo.bonifacio wrote:
envKey :: EnvItem (Key, a) -> String envKey EnvItem (key, value) = key
envValue :: EnvValue(Key, a) -> a envValue EnvItem (key, value) = value
But this is resulting in the error: [Constructor "EnvItem" must have exactly 1 argument in pattern]
You need to parenthesize the constructor. envValue (EnvItem (_,value)) = value (The _ indicates that you're not using that item, rather than giving it a name that won't be used.) Why do you need to do this? Because you can pass functions around, and a constructor is a function. But your type says you don't want a bare function there, so the compiler complains. -- brandon s. allbery [solaris,freebsd,perl,pugs,haskell] allbery@kf8nh.com system administrator [openafs,heimdal,too many hats] allbery@ece.cmu.edu electrical and computer engineering, carnegie mellon university KF8NH