StrictData and the parser

[Edward Z. Yang]

Excerpts from Johan Tibell's message of 2015-06-04 16:52:30 -0700:
> I guess we should parse it as T a (~b), just as we have unary minus bind
> "tighter" with the following token.

Not in all contexts.

It is true that if you have 'data SLPair a b = SLP a ~ b' you want to
parse 'SLP a (~b)'

But if you have 'Maybe a ~ b' you want to parse '(Maybe a) ~ b'.

But in GADTs, if you have

    data SLPair a b where
        SLP :: a -> ~ b -> SLPair a b

you want a -> (~ b) -> SLPair a b

If the twiddle is not immediately after an arrow you don't want
that, e.g.

    data T a b where
        T :: a -> a ~ b -> SLPair a b

you want T :: a -> (a ~ b) -> SLPair a b

Edward