Add UNPACK support to Template Haskell

[mikhail.vorozhtsov]

I've just hacked it in:

$ ghci -XTemplateHaskell
GHCi, version 7.1.20110630: http://www.haskell.org/ghc/  :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer-gmp ... linking ... done.
Loading package base ... linking ... done.
Loading package ffi-1.0 ... linking ... done.
λ> import Language.Haskell.TH
λ> runQ [d| data T = T {-# UNPACK #-} !Int |]
Loading package array-0.3.0.2 ... linking ... done.
Loading package containers-0.4.0.0 ... linking ... done.
Loading package pretty-1.0.2.0 ... linking ... done.
Loading package template-haskell ... linking ... done.
[DataD [] T [] [NormalC T [(Unpacked,ConT GHC.Types.Int)]] []]
λ>

TH.hs:

{-# LANGUAGE TemplateHaskell #-}

module TH where

import Language.Haskell.TH

d :: Q [Dec]
d = return [DataD [] n [] [NormalC n [(Unpacked,ConT ''Int)]] []]
  where n = mkName "T" 

Main.hs:

{-# LANGUAGE TemplateHaskell #-}

import TH

$(d)

instance Show T where
  show (T i) = show i

main = putStrLn $ show (T 10)

Compiling and running:

$ ghc -ddump-splices -fforce-recomp Main.hs
[1 of 2] Compiling TH               ( TH.hs, TH.o )
[2 of 2] Compiling Main             ( Main.hs, Main.o )
Loading package ghc-prim ... linking ... done.
Loading package integer-gmp ... linking ... done.
Loading package base ... linking ... done.
Loading package ffi-1.0 ... linking ... done.
Loading package pretty-1.0.2.0 ... linking ... done.
Loading package array-0.3.0.2 ... linking ... done.
Loading package containers-0.4.0.0 ... linking ... done.
Loading package template-haskell ... linking ... done.
Main.hs:1:1: Splicing declarations
    d
  ======>
    Main.hs:5:3
    data T = T {-# UNPACK #-} !Int
Linking Main ...
$ ./Main
10

Please consider merging.

[mikhail.vorozhtsov]

Patch for the template-haskell library

[mikhail.vorozhtsov]

Patch for the GHC

[simonpj]

Thanks. Seemed to fit into the existing data types quite nicely. I applied yoru patches. (Something went wrong with using your patches verbatim, so you are only credited as author in the commit message.)

commit 65c019407134fcb0c6b7c9d2038ba07c52e2a6c2
Author: Simon Peyton Jones <simonpj@microsoft.com>
Date:   Fri Jul 15 21:15:43 2011 +0100

    Extend Template Haskell to support the UNPACk pragma on data constructors
    
    (Work done by mikhail.vorozhtsov.)

 compiler/hsSyn/Convert.lhs |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

and in the TH lib

commit 15f68f57ca685933d18d88655e91ea692ccd198f
Author: Simon Peyton Jones <simonpj@microsoft.com>
Date:   Mon Jul 18 23:25:51 2011 +0100

    Add TH support for UNPACK pragmas (Trac #5290)
    
    The extension is nice, because it just adds an extra
    constructor to the existing data type 'Strict'.
    
    Thanks to Mikhail Vorozhtsov.

 Language/Haskell/TH/Lib.hs    |    3 ++-
 Language/Haskell/TH/Ppr.hs    |    1 +
 Language/Haskell/TH/Syntax.hs |    2 +-
 3 files changed, 4 insertions(+), 2 deletions(-)

Could merge to 7.2

Simon

[igloo]

I think it's too late for new features in the 7.2 branch, sorry.