Merijn, Perhaps only for the sake of discussion: have you considered doing something at the type-level instead of using TH? I mean that you could change the type of 42 from `forall a. Num a => a` to `forall a. HasIntLiteral a '42 => a` where HasIntegerLiteral is a type class of kind `* -> 'Integer -> Constraint` and people can instantiate it for their types:
class HasIntegerLiteral (a :: *) (k :: 'Integer) where literal :: a The desugarer could then just generate an invocation of "literal". An advantage would be that you don't need TH (although you do need DataKinds and type-level computation). Specifically, type-checking remains decidable and you can do it in safe haskell and so on. I haven't thought this through very far, so there may be other advantages/disadvantages/glaring-holes-in-the-idea that I'm missing. Regards, Dominique 2015-02-06 11:07 GMT+01:00 Merijn Verstraaten <mer...@inconsistent.nl>: > And no one of my proofreaders noticed that >.> > > I would propose to have the extension replace the 'fromString "foo"', > 'fromIntegral 5' and 'fromList [1,2,3]' calls (for monomorphic cases) in the > AST with the relevant Typed TH splice. > > I considered quasi-quotation initially too, but there's no quasi quotation > syntax for Typed TH. I'm guessing that's just an oversight, but I'd really be > in favour of adding a typed quasiquoter too. Similarly to thinking we should > have an easier way to obtain Lift instances since, to me at least, it seems > that the Lift instance for most ADTs should be fairly trivial? > > I'll quickly clarify the proposal on the wiki :) > > Cheers, > Merijn > >> On 5 Feb 2015, at 22:48, Simon Peyton Jones <simo...@microsoft.com> wrote: >> >> I'm all for it. Syntax sounds like the main difficulty. Today you could >> use quasiquotatoin >> [even| 38 |] >> and get the same effect as $$(validate 38). But it's still noisy. >> >> So: what is the non-noisy scheme you want to propose? You don't quite get >> to that in the wiki page! >> >> Simon >> >> | -----Original Message----- >> | From: ghc-devs [mailto:ghc-devs-boun...@haskell.org] On Behalf Of Merijn >> | Verstraaten >> | Sent: 05 February 2015 14:46 >> | To: ghc-d...@haskell.org; GHC users >> | Subject: Proposal: ValidateMonoLiterals - Initial bikeshed discussion >> | >> | I've been repeatedly running into problems with overloaded literals and >> | partial conversion functions, so I wrote up an initial proposal >> | (https://ghc.haskell.org/trac/ghc/wiki/ValidateMonoLiterals) and I'd like >> | to commence with the bikeshedding and hearing other opinions :) >> | >> | Cheers, >> | Merijn > > > _______________________________________________ > Glasgow-haskell-users mailing list > Glasgow-haskell-users@haskell.org > http://www.haskell.org/mailman/listinfo/glasgow-haskell-users > _______________________________________________ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
