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| author | Simon Peyton Jones <simonpj@microsoft.com> | 2016-03-29 09:57:06 +0100 |
|---|---|---|
| committer | Simon Peyton Jones <simonpj@microsoft.com> | 2016-03-31 08:02:29 +0100 |
| commit | 8f66bac9ba4c3ebe6c26b0c72e03b6754782ecbe (patch) | |
| tree | de46ce2a17ec085aef6c88e2ee5a8e2a1483b30a | |
| parent | 24d761531cfc18152598becc0aeb90376fd19198 (diff) | |
| download | haskell-8f66bac9ba4c3ebe6c26b0c72e03b6754782ecbe.tar.gz | |
Comments only
| -rw-r--r-- | compiler/basicTypes/DataCon.hs | 16 | ||||
| -rw-r--r-- | compiler/typecheck/TcSimplify.hs | 2 |
2 files changed, 8 insertions, 10 deletions
diff --git a/compiler/basicTypes/DataCon.hs b/compiler/basicTypes/DataCon.hs index 1e4af2d475..9a754dd423 100644 --- a/compiler/basicTypes/DataCon.hs +++ b/compiler/basicTypes/DataCon.hs @@ -291,10 +291,9 @@ data DataCon -- dcRepTyCon = T -- In general, the dcUnivTyVars are NOT NECESSARILY THE SAME AS THE TYVARS - -- FOR THE PARENT TyCon. With GADTs the data con might not even have - -- the same number of type variables! - -- [This is a change (Oct05): previously, vanilla datacons guaranteed to - -- have the same type variables as their parent TyCon, but that seems ugly.] + -- FOR THE PARENT TyCon. (This is a change (Oct05): previously, vanilla + -- datacons guaranteed to have the same type variables as their parent TyCon, + -- but that seems ugly.) dcVanilla :: Bool, -- True <=> This is a vanilla Haskell 98 data constructor -- Its type is of form @@ -307,12 +306,11 @@ data DataCon -- The declaration format is held in the TyCon (algTcGadtSyntax) -- Universally-quantified type vars [a,b,c] + -- INVARIANT: length matches arity of the dcRepTyCon + -- INVARIANT: result type of data con worker is exactly (T a b c) dcUnivTyVars :: [TyVar], -- Two linked fields dcUnivTyBinders :: [TyBinder], -- see Note [TyBinders in DataCons] - -- INVARIANT: length matches arity of the dcRepTyCon - -- - -- INFARIANT: result type of (rep) data con is exactly (T a b c) -- Existentially-quantified type vars [x,y] dcExTyVars :: [TyVar], -- Two linked fields @@ -441,8 +439,8 @@ Specifically: the corresponding tyvar in the TyVars list. * Each Visibilty flag (va, vb, etc) is Invisible or Specified. - None are Visible. (See Note [No Visible TyBinder in terms]; - a DataCon is a term-level function.) + None are Visible. (A DataCon is a term-level function; see + Note [No Visible TyBinder in terms] in TyCoRep.) Why store these fields redundantly? Purely convenience. In most places in GHC, it's just the TyVars that are needed, so that's what's diff --git a/compiler/typecheck/TcSimplify.hs b/compiler/typecheck/TcSimplify.hs index 51a35884ef..3adb77eb9d 100644 --- a/compiler/typecheck/TcSimplify.hs +++ b/compiler/typecheck/TcSimplify.hs @@ -768,7 +768,7 @@ decideQuantification apply_mr sigs name_taus constraints -- to *. So, don't grow the kvs. ; constraints <- TcM.zonkTcTypes constraints - -- quantiyTyVars turned some meta tyvars into + -- quantifyTyVars turned some meta tyvars into -- quantified skolems, so we have to zonk again ; let theta = pickQuantifiablePreds (mkVarSet qtvs) constraints |