[ghc-steering-committee] Record dot notation

[Joachim Breitner]

Hi Cale,

thanks for making sure the discussion isn’t just about whitespace, but
also whether we want this at all!

Am Dienstag, den 11.02.2020, 12:28 -0500 schrieb Cale Gibbard:
> Since I seem to be of the opinion that this wouldn't be a good
> inclusion while most everyone else is more convinced that *something*
> along these lines is needed or desirable

My assumption here is that to some people, the lack for nice record
access syntax is a big pain, else they would not bother with a proposal
like this. In most of my Haskell programming, my own pain level wasn't
too high (although prefixed field names are a bit ugly). I had one
rather special case where I wish I could use Haskell as an “exectuable
specification pseudocode langauge”, and the lack of nice record syntax
killed that idea. This proposal might have helped some here (but only
some, not all).

So I can’t really refute your point that this might not be needed.


You bring up some points about whether this doesn't go far enough (row
polymorphism etc.). But this proposal really only add syntax for an
existing feature (HasField), so maybe this is not the right place for a
semantic critique of HasField? Of course it is a valid point to say
that HasField is a feature that is not “good enough” to deserve a slice
of the precious “.” operator.


> And if this is not about the concrete syntax of using dot
> for yet another thing, then what is it about? We presumably already
> have reasonably convenient ways of expressing everything here, don't
> we?

I guess to some it isn't reasonable to write `f (getField @"lbl" r)`…?

Cheers,
Joachim
-- 
Joachim Breitner
  mail at joachim-breitner.de
  http://www.joachim-breitner.de/