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| author | Bartosz Nitka <niteria@gmail.com> | 2016-05-12 06:44:52 -0700 |
|---|---|---|
| committer | Bartosz Nitka <niteria@gmail.com> | 2016-05-12 06:45:13 -0700 |
| commit | 01bc10965d993babf6c2c35d340655f683ba0ca2 (patch) | |
| tree | 2b1975779472876822013bbda462e4fb8a996c22 | |
| parent | 697143064c271c57a69e80850a768449f8bcf4ca (diff) | |
| download | haskell-01bc10965d993babf6c2c35d340655f683ba0ca2.tar.gz | |
Document zonkTyCoVarsAndFV determinism
I've changed it to use nonDetEltsUFM and documented why
it's OK.
Test Plan: it builds
Reviewers: bgamari, austin, simonmar, goldfire, simonpj
Reviewed By: simonpj
Subscribers: thomie
Differential Revision: https://phabricator.haskell.org/D2204
GHC Trac Issues: #4012
| -rw-r--r-- | compiler/typecheck/TcMType.hs | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/compiler/typecheck/TcMType.hs b/compiler/typecheck/TcMType.hs index 8ad9aba8cd..94c4947be5 100644 --- a/compiler/typecheck/TcMType.hs +++ b/compiler/typecheck/TcMType.hs @@ -108,6 +108,7 @@ import FastString import SrcLoc import Bag import Pair +import UniqFM import qualified GHC.LanguageExtensions as LangExt import Control.Monad @@ -1230,7 +1231,11 @@ zonkTyCoVar tv | isTcTyVar tv = zonkTcTyVar tv -- painful to make them into TcTyVars there zonkTyCoVarsAndFV :: TyCoVarSet -> TcM TyCoVarSet -zonkTyCoVarsAndFV tycovars = tyCoVarsOfTypes <$> mapM zonkTyCoVar (varSetElems tycovars) +zonkTyCoVarsAndFV tycovars = + tyCoVarsOfTypes <$> mapM zonkTyCoVar (nonDetEltsUFM tycovars) + -- It's OK to use nonDetEltsUFM here because we immediately forget about + -- the ordering by turning it into a nondeterministic set and the order + -- of zonking doesn't matter for determinism. -- Takes a list of TyCoVars, zonks them and returns a -- deterministically ordered list of their free variables. |