haskell-decl-scan doesn't deal with TypeOperators

[ivan-m]

When you have a file with the following:

{-# LANGUAGE TypeOperators #-}

type x :^: y = y -> x

haskell-decl-scan will erroneously list this under Datatypes -> x.

I believe it's because this:

(if (looking-at "[ \t]*\\(\\sw+\\)")
              (progn
                (setq name (match-string-no-properties 1))
                (setq name-pos (match-beginning 1))
                (setq type 'datatype)))

just takes the first identifier listed there (without considering whether it's a valid name for a data type).

On the other hand, if we define the datatype as follows:

type (:^:) x y = y -> x

then haskell-decl-scan doesn't pick it up at all.

[gracjan]

This issue has not seen activity for a very long time. Is this still something we should be concerned about?

[gracjan]

Related #1122.