diff options
Diffstat (limited to 'compiler/types/Coercion.hs')
| -rw-r--r-- | compiler/types/Coercion.hs | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/compiler/types/Coercion.hs b/compiler/types/Coercion.hs index 254f76ca31..8e4efbac50 100644 --- a/compiler/types/Coercion.hs +++ b/compiler/types/Coercion.hs @@ -209,7 +209,7 @@ pprCoAxBranchLHS :: TyCon -> CoAxBranch -> SDoc -- a conflict between equations (FamInst.conflictInstErr) -- For type families the RHS is important; for data families not so. -- Indeed for data families the RHS is a mysterious internal --- type constructor, so we suppress it (Trac #14179) +-- type constructor, so we suppress it (#14179) -- See FamInstEnv Note [Family instance overlap conflicts] pprCoAxBranchLHS = ppr_co_ax_branch pp_rhs where @@ -342,7 +342,7 @@ Notes: where co :: (forall a. ty) ~ (ty1 -> ty2) Here 'co' is insoluble, but we don't want to crash in decoposePiCos. So decomposePiCos carefully tests both sides of the coercion to check - they are both foralls or both arrows. Not doing this caused Trac #15343. + they are both foralls or both arrows. Not doing this caused #15343. -} decomposePiCos :: HasDebugCallStack @@ -718,7 +718,7 @@ mkAppCo co arg | Just (ty1, r) <- isReflCo_maybe co , Just (tc, tys) <- splitTyConApp_maybe ty1 - -- Expand type synonyms; a TyConAppCo can't have a type synonym (Trac #9102) + -- Expand type synonyms; a TyConAppCo can't have a type synonym (#9102) = mkTyConAppCo r tc (zip_roles (tyConRolesX r tc) tys) where zip_roles (r1:_) [] = [downgradeRole r1 Nominal arg] @@ -2292,10 +2292,10 @@ Suppose we need `coercionKind (ForAllCo a1 (ForAllCo a2 ... (ForAllCo an co)...) )`. We do not want to perform `n` single-type-variable substitutions over the kind of `co`; rather we want to do one substitution which substitutes for all of `a1`, `a2` ... simultaneously. If we do one -at a time we get the performance hole reported in Trac #11735. +at a time we get the performance hole reported in #11735. Solution: gather up the type variables for nested `ForAllCos`, and -substitute for them all at once. Remarkably, for Trac #11735 this single +substitute for them all at once. Remarkably, for #11735 this single change reduces /total/ compile time by a factor of more than ten. -} @@ -2334,7 +2334,7 @@ coercionRole = go {- Note [Nested InstCos] ~~~~~~~~~~~~~~~~~~~~~ -In Trac #5631 we found that 70% of the entire compilation time was +In #5631 we found that 70% of the entire compilation time was being spent in coercionKind! The reason was that we had (g @ ty1 @ ty2 .. @ ty100) -- The "@s" are InstCos where @@ -2342,7 +2342,7 @@ where If we deal with the InstCos one at a time, we'll do this: 1. Find the kind of (g @ ty1 .. @ ty99) : forall a100. phi' 2. Substitute phi'[ ty100/a100 ], a single tyvar->type subst -But this is a *quadratic* algorithm, and the blew up Trac #5631. +But this is a *quadratic* algorithm, and the blew up #5631. So it's very important to do the substitution simultaneously; cf Type.piResultTys (which in fact we call here). |