Re: [Haskell-cafe] Haskell syntax inside QuasiQuote

26 Oct 2008

      I've just uploaded an alpha version of the translation to hackage:

http://hackage.haskell.org/cgi-bin/hackage-scripts/package/haskell-src-meta-...

(I starting thinking after I uploaded that maybe haskell-src-th is a
better name..)

Here's one strategy for a haskell QQ:

------------------------------------------------------------
module HsQQ where

import Language.Haskell.Meta
import Language.Haskell.TH.Lib
import Language.Haskell.TH.Quote
import Language.Haskell.TH.Syntax

-- |
-- > ghci> [$hs|\x -> (x,x)|] 42
-- > (42,42)
-- > ghci> (\[$hs|a@(x,_)|] -> (a,x)) (42,88)
-- > ((42,88),42)
hs :: QuasiQuoter
hs = QuasiQuoter
      (either fail transformE . parseExp)
      (either fail transformP . parsePat)

transformE :: Exp -> ExpQ
transformE = return

transformP :: Pat -> PatQ
transformP = return
------------------------------------------------------------

I'll post updates as I add to the pkg over the next few days.

Cheers,
Matt

On 10/21/08, Reiner Pope  wrote:
...
It sounds like you're doing exactly what I'm looking for. I look forward to
more.
Reiner
On Tue, Oct 21, 2008 at 4:28 PM, Matt Morrow  wrote:
...
...
Is there a simple way to do this, i.e. using existing libraries?
Yes indeed. I'll be traveling over the next two days, and am shooting
for a fully functional hackage release by mid next week.
...
What I need is a Haskell expression parser which outputs values of type
Language.Haskell.TH.Syntax.QExp, but I can't see one available in the TH
libraries, or in the haskell-src(-exts) libraries.
My strategy is to use the existing haskell-src-exts parser, then
translate that AST to the TH AST.
Once I've got settled in one place, I'll follow up with a brain dump :)
...
Cheers,
Reiner
Matt
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