id,summary,reporter,owner,description,type,status,priority,milestone,component,version,resolution,keywords,cc,os,architecture,failure,difficulty,testcase,blockedby,blocking,related
3788,"Improved message for GHC ""No instance for"" Errors",rhapsodyv,,"Hi,

I would like to propose a modification in the ghc message for ""no
instance for"" errors.
In the message, the ghc tells that there's no instance for the type
you are using and it give you a hint that you can fix it adding a new
instance for your type. But it don't tell me any instance alternative
that already exists. So, if I don't know the correct type, I need to
look at the documentation.

At least for me, I get this message when I'm using the function in the
wrong way or when I forget to specify the some function signature.
It's quite rare the I want to add a new instance.
Of course that it's not a problem to look at the documentation, but
improving it can save a significant time and help the beginers to
guess the error and how fix it.

In C++ and Java, when I use g++ or javac and I make a wrong
overloading, the compiler show me some alternatives. I think it help
more than tell me to add a new overload to the function.

It's possible to do it in ghc?",bug,closed,normal,6.12.2,Compiler,6.10.4,wontfix,errors,,Unknown/Multiple,Unknown/Multiple,None/Unknown,,,,,