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| author | Simon Peyton Jones <simonpj@microsoft.com> | 2015-08-07 12:32:48 +0100 |
|---|---|---|
| committer | Simon Peyton Jones <simonpj@microsoft.com> | 2015-08-07 12:34:12 +0100 |
| commit | a192d6b46d86141b7f184df219b36c13c420e6ef (patch) | |
| tree | 1bd3281aa8f5d533cd817fc65e201c9816dbc144 | |
| parent | 79e0a10e541724713f1149c468ba966b7fc819d3 (diff) | |
| download | haskell-a192d6b46d86141b7f184df219b36c13c420e6ef.tar.gz | |
Comments only
| -rw-r--r-- | compiler/typecheck/TcCanonical.hs | 4 | ||||
| -rw-r--r-- | compiler/typecheck/TcFlatten.hs | 9 | ||||
| -rw-r--r-- | compiler/typecheck/TcSMonad.hs | 2 |
3 files changed, 8 insertions, 7 deletions
diff --git a/compiler/typecheck/TcCanonical.hs b/compiler/typecheck/TcCanonical.hs index f37ad3e6dc..ed3955d0f3 100644 --- a/compiler/typecheck/TcCanonical.hs +++ b/compiler/typecheck/TcCanonical.hs @@ -1128,7 +1128,7 @@ canEqTyVarTyVar ev eq_rel swapped tv1 tv2 | incompat_kind = incompatibleKind ev xi1 k1 xi2 k2 -- We don't do this any more --- See Note [Orientation of equalities with fmvs] in TcSMonad +-- See Note [Orientation of equalities with fmvs] in TcFlatten -- | isFmvTyVar tv1 = do_fmv swapped tv1 xi1 xi2 co1 co2 -- | isFmvTyVar tv2 = do_fmv (flipSwap swapped) tv2 xi2 xi1 co2 co1 @@ -1159,7 +1159,7 @@ canEqTyVarTyVar ev eq_rel swapped tv1 tv2 , cc_rhs = xi2, cc_eq_rel = eq_rel }) {- We don't do this any more - See Note [Orientation of equalities with fmvs] in TcSMonad + See Note [Orientation of equalities with fmvs] in TcFlatten -- tv1 is the flatten meta-var do_fmv swapped tv1 xi1 xi2 co1 co2 | same_kind diff --git a/compiler/typecheck/TcFlatten.hs b/compiler/typecheck/TcFlatten.hs index 9df06908dd..052c158cfc 100644 --- a/compiler/typecheck/TcFlatten.hs +++ b/compiler/typecheck/TcFlatten.hs @@ -264,8 +264,9 @@ This is a real dilemma. CURRENT SOLUTION: CFunEqCan F fmv ~ fmv, because fmv := F fmv would make an ininite type. Instead we unify fmv:=a, AND record that we have done so. - If any such "non-CFunEqCan unifications" take place, iterate the - entire process. This is done by the 'go' loop in solveSimpleWanteds. + If any such "non-CFunEqCan unifications" take place (in + unflatten_eq in TcFlatten.unflatten) iterate the entire process. + This is done by the 'go' loop in solveSimpleWanteds. This story does not feel right but it's the best I can do; and the iteration only happens in pretty obscure circumstances. @@ -1368,7 +1369,7 @@ unflatten tv_eqs funeqs ; funeqs <- foldrBagM (unflatten_funeq dflags) emptyCts funeqs ; traceTcS "Unflattening 1" $ braces (pprCts funeqs) - -- Step 2: unify the irreds, if possible + -- Step 2: unify the tv_eqs, if possible ; tv_eqs <- foldrBagM (unflatten_eq dflags tclvl) emptyCts tv_eqs ; traceTcS "Unflattening 2" $ braces (pprCts tv_eqs) @@ -1376,7 +1377,7 @@ unflatten tv_eqs funeqs ; funeqs <- mapBagM finalise_funeq funeqs ; traceTcS "Unflattening 3" $ braces (pprCts funeqs) - -- Step 4: remove any irreds that look like ty ~ ty + -- Step 4: remove any tv_eqs that look like ty ~ ty ; tv_eqs <- foldrBagM finalise_eq emptyCts tv_eqs ; let all_flat = tv_eqs `andCts` funeqs diff --git a/compiler/typecheck/TcSMonad.hs b/compiler/typecheck/TcSMonad.hs index cd3d3c977b..3721975d3e 100644 --- a/compiler/typecheck/TcSMonad.hs +++ b/compiler/typecheck/TcSMonad.hs @@ -994,7 +994,7 @@ Note [Examples of how the inert_model helps completeness] [D] d4: fmv2 ~ a At this point we are stuck so we unflatten this set: - See Note [Orientation of equalities with fmvs] + See Note [Orientation of equalities with fmvs] in TcFlatten [W] w1: F fmv2 ~ fmv1 [W] w2: UnF fmv1 ~ fmv2 [W] w5: fmv1 ~ fsk1 |