[commit: ghc] type-nats-simple: Add a function to get all inert fun-eqs for the given tycon. (fb3f5d7)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : type-nats-simple
Link       : http://ghc.haskell.org/trac/ghc/changeset/fb3f5d7db1fbd31b215befa4f5199a9dbd30d5d5/ghc

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

commit fb3f5d7db1fbd31b215befa4f5199a9dbd30d5d5
Author: Iavor S. Diatchki <iavor.diatchki at gmail.com>
Date:   Sat Sep 7 17:07:23 2013 -0700

    Add a function to get all inert fun-eqs for the given tycon.


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

fb3f5d7db1fbd31b215befa4f5199a9dbd30d5d5
 compiler/typecheck/TcSMonad.lhs |   13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/compiler/typecheck/TcSMonad.lhs b/compiler/typecheck/TcSMonad.lhs
index 39337ad..d9fc9da 100644
--- a/compiler/typecheck/TcSMonad.lhs
+++ b/compiler/typecheck/TcSMonad.lhs
@@ -72,6 +72,7 @@ module TcSMonad (
     modifyInertTcS,
     insertInertItemTcS, partitionCCanMap, partitionEqMap,
     getRelevantCts, extractRelevantInerts,
+    getInertsFunEqTyCon,
     CCanMap(..), CtTypeMap, CtFamHeadMap, CtPredMap,
     PredMap, FamHeadMap,
     partCtFamHeadMap, lookupFamHead, lookupSolvedDict,
@@ -827,6 +828,18 @@ checkAllSolved
                      || unsolved_dicts || unsolved_funeqs
                      || not (isEmptyBag (inert_insols icans)))) }
 
+
+{- Get inert function equation constraints that have the given tycon
+in their head.  Not that the constraints remain in the inert set.
+We use this to check for derived interactions with built-in type-function
+constructors. -}
+getInertsFunEqTyCon :: TyCon -> TcS [Ct]
+getInertsFunEqTyCon tc =
+  do is <- getTcSInerts
+     let mp = unFamHeadMap $ inert_funeqs $ inert_cans is
+     return $ lookupTypeMapTyCon mp tc
+
+
 extractRelevantInerts :: Ct -> TcS Cts
 -- Returns the constraints from the inert set that are 'relevant' to react with 
 -- this constraint. The monad is left with the 'thinner' inerts.