[commit: ghc] tc-untouchables: Implement 'left' and 'right' coercions (af7cc99)

Repository : ssh://darcs.haskell.org//srv/darcs/ghc

On branch  : tc-untouchables

http://hackage.haskell.org/trac/ghc/changeset/af7cc9953217d74e88d4d21512e957edd8e97ec9

>---------------------------------------------------------------

commit af7cc9953217d74e88d4d21512e957edd8e97ec9
Author: Simon Peyton Jones <[email protected]>
Date:   Mon Sep 17 11:34:28 2012 +0100

    Implement 'left' and 'right' coercions
    
    This patch finally adds 'left' and 'right' coercions back into
    GHC.  Trac #7205 gives the details.
    
    The main change is to add a new constructor to Coercion:
    
      data Coercion
        = ...
        | NthCo  Int         Coercion     -- OLD, still there
        | LRCo   LeftOrRight Coercion     -- NEW
    
      data LeftOrRight = CLeft | CRight
    
    Plus:
      * Similar change to TcCoercion
      * Use LRCo when decomposing AppTys
      * Coercion optimisation needs to handle left/right
    
    The rest is just knock-on effects.

 compiler/coreSyn/CoreLint.lhs        |   13 ++++++++
 compiler/coreSyn/ExternalCore.lhs    |    3 ++
 compiler/coreSyn/MkExternalCore.lhs  |    5 +++
 compiler/coreSyn/PprExternalCore.lhs |    4 ++
 compiler/coreSyn/TrieMap.lhs         |   22 ++++++++++---
 compiler/deSugar/DsBinds.lhs         |    1 +
 compiler/iface/BinIface.hs           |   14 ++++++++-
 compiler/iface/IfaceType.lhs         |    5 ++-
 compiler/iface/TcIface.lhs           |    1 +
 compiler/typecheck/TcCanonical.lhs   |   14 ++-------
 compiler/typecheck/TcEvidence.lhs    |   14 +++++++--
 compiler/typecheck/TcHsSyn.lhs       |    1 +
 compiler/typecheck/TcType.lhs        |    1 +
 compiler/types/Coercion.lhs          |   31 +++++++++++++++++--
 compiler/types/OptCoercion.lhs       |   56 ++++++++++++++++++++++++++++-----
 15 files changed, 152 insertions(+), 33 deletions(-)


Diff suppressed because of size. To see it, use:

    git show af7cc9953217d74e88d4d21512e957edd8e97ec9