indeed .. and we can reasonably say "lets deal with the bandaid in one go by cleaning it up in the next standard"
Thanks Carter/Brandon, the reason for asking how we should go about the discussion was exactly: where/how are we going to maximise the chance of finding out what code is out there, and how disruptive any 'clean up' might be?
Ghc has occasionally made breaking releases (not saying that's what we want to do), usually with some advance warning/deprecation period. And generally the Haskell community has accommodated that with understanding of the decision, to fix their code.
so what would the next gen look like?
eg: fresh variables get the usual implicit forall at the front of the type, and everything else either needs an explicit quantifier OR it refers to the outer implicit quantified variable?
I wanted to avoid discussing 'next gen' in possibly-obscure/write-only mailing lists; and preferably get the discussion where posterity can see the reasoning/examination of options.
"fresh variables get the usual implicit forall" is what happens now. (It's just that the User Guide explains it really badly -- I'm trying to fix that separately
https://ghc.haskell.org/trac/ghc/ticket/15146 .) If the outer variable(s) are not explicitly forall-quantified, then even same-named variables count as fresh. IOW merely putting a `forall` can change the meaning of a program -- that's what causes the most confusion (judging by SO).
The exception is variables bound in a pattern signature for an existentially-quantified data constructor: they *must* be fresh. This is hard for a reader to follow because the pattern signature with data constructor looks the same whether or not the constructor is existentially-quantified. What's worse a constructor might have a mix of existential and universal variables.
AntC