Re: expanding type synonyms in error messages

Clang (and recent GCC versions) do something like this in error messages. They say MyString (aka std::string<...lots of junk...>) is uncool maybe a similar system would help you? Cheers, Gabor On 6/16/15, Ömer Sinan Ağacan wrote:

Hi all,

While working with complex types with lots of arguments etc. errors are becoming annoying very fast. For example, GHC prints errors in this way:

Expected type: <type without any synonyms> Actual type: <type with synonyms>

Now I have to expand that synonym in my head to understand the error.

I was wondering if implementing something like this is possible:

In type error messages, GHC also prints types that are cleaned from type synonyms. Maybe something like this:

Expected type: <type1> (without synonyms): Actual type: <type2> (without synonyms):

If this is not always desirable for some reason, we can hide this behavior behind a flag.

What do GHC devs think about this? Is this, in theory, possible to do? How hard would it be to implement this?

Thanks. _______________________________________________ ghc-devs mailing list ghc-devs@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs