#7205: Re-introduce left/right coercion decomposition
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Reporter: simonpj | Owner:
Type: feature request | Status: new
Priority: normal | Milestone:
Component: Compiler | Version: 7.4.2
Keywords: | Os: Unknown/Multiple
Architecture: Unknown/Multiple | Failure: None/Unknown
Difficulty: Unknown | Testcase:
Blockedby: | Blocking:
Related: |
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Comment(by simonpj@…):
commit af7cc9953217d74e88d4d21512e957edd8e97ec9
{{{
Author: Simon Peyton Jones <simo...@microsoft.com>
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(-)
}}}
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7205#comment:4>
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