-%
+
% (c) The University of Glasgow 2006
% (c) The GRASP Project, Glasgow University, 1992-2002
%
\begin{code}
+{-# OPTIONS -w #-}
+-- The above warning supression flag is a temporary kludge.
+-- While working on this module you are encouraged to remove it and fix
+-- any warnings in the module. See
+-- http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings
+-- for details
+
module TcRnTypes(
TcRnIf, TcRn, TcM, RnM, IfM, IfL, IfG, -- The monad is opaque outside this module
TcRef,
-- (Ids defined in this module start in the local envt,
-- though they move to the global envt during zonking)
- tcg_type_env_var :: TcRef TypeEnv,
+ tcg_type_env_var :: TcRef TypeEnv,
-- Used only to initialise the interface-file
-- typechecker in initIfaceTcRn, so that it can see stuff
-- bound in this module when dealing with hi-boot recursions
-- Incremented when going inside a bracket,
-- decremented when going inside a splice
-- NB: ThLevel is one greater than the 'n' in Fig 2 of the
- -- original "Template meta-programmign for Haskell" paper
+ -- original "Template meta-programming for Haskell" paper
impLevel, topLevel :: ThLevel
topLevel = 1 -- Things defined at top level of this module
-- GADT refinement
instance Outputable TcTyThing where -- Debugging only
- ppr (AGlobal g) = ppr g
+ ppr (AGlobal g) = pprTyThing g
ppr elt@(ATcId {}) = text "Identifier" <>
ifPprDebug (brackets (ppr (tct_id elt) <> dcolon <> ppr (tct_type elt) <> comma
<+> ppr (tct_level elt) <+> ppr (tct_co elt)))
represent implication constraints 'forall tvs. (reft, given) => wanted'
and equality constraints 'co :: ty1 ~ ty2'.
+NB: Equalities occur in two flavours:
+
+ (1) Dict {tci_pred = EqPred ty1 ty2}
+ (2) EqInst {tci_left = ty1, tci_right = ty2, tci_co = coe}
+
+The former arises from equalities in contexts, whereas the latter is used
+whenever the type checker introduces an equality (e.g., during deferring
+unification).
+
+I am not convinced that this duplication is necessary or useful! -=chak
+
\begin{code}
data Inst
= Dict {
-- Includes coercion variables
-- mentioned in tci_reft
tci_reft :: Refinement,
- tci_given :: [Inst], -- Only Dicts
+ tci_given :: [Inst], -- Only Dicts and EqInsts
-- (no Methods, LitInsts, ImplicInsts)
- tci_wanted :: [Inst], -- Only Dicts and ImplicInsts
+ tci_wanted :: [Inst], -- Only Dicts, EqInst, and ImplicInsts
-- (no Methods or LitInsts)
tci_loc :: InstLoc
| EqInst { -- delayed unification of the form
-- co :: ty1 ~ ty2
- tci_left :: TcType, -- ty1
- tci_right :: TcType, -- ty2
+ tci_left :: TcType, -- ty1 -- both types are...
+ tci_right :: TcType, -- ty2 -- ...free of boxes
tci_co :: Either -- co
- TcTyVar -- a wanted equation, with a hole, to be
- -- filled with a witness for the equality
- -- for equation generated by the
- -- unifier, 'ty1' is the actual and
- -- 'ty2' the expected type
- Coercion, -- a given equation, with a coercion
- -- witnessing the equality
- -- a coercion that originates from a
- -- signature or a GADT is a CoVar, but
- -- after normalisation of coercions,
- -- they can be arbitrary Coercions
- -- involving constructors and
- -- pseudo-constructors like sym and
- -- trans.
+ TcTyVar -- - a wanted equation, with a hole, to be
+ -- filled with a witness for the equality;
+ -- for equation arising from deferring
+ -- unification, 'ty1' is the actual and
+ -- 'ty2' the expected type
+ Coercion, -- - a given equation, with a coercion
+ -- witnessing the equality;
+ -- a coercion that originates from a
+ -- signature or a GADT is a CoVar, but
+ -- after normalisation of coercions, they
+ -- can be arbitrary Coercions involving
+ -- constructors and pseudo-constructors
+ -- like sym and trans.
tci_loc :: InstLoc,
tci_name :: Name -- Debugging help only: this makes it easier to
-- The rest are all occurrences: Insts that are 'wanted'
-------------------------------------------------------
| OccurrenceOf Name -- Occurrence of an overloaded identifier
+ | SpecPragOrigin Name -- Specialisation pragma for identifier
| IPOccOrigin (IPName Name) -- Occurrence of an implicit parameter
| LiteralOrigin (HsOverLit Name) -- Occurrence of a literal
+ | NegateOrigin -- Occurrence of syntactic negation
| ArithSeqOrigin (ArithSeqInfo Name) -- [x..], [x..y] etc
| PArrSeqOrigin (ArithSeqInfo Name) -- [:x..y:] and [:x,y..z:]
+ | TupleOrigin -- (..,..)
| InstSigOrigin -- A dict occurrence arising from instantiating
-- a polymorphic type during a subsumption check
+ | ExprSigOrigin -- e :: ty
| RecordUpdOrigin
+ | ViewPatOrigin
| InstScOrigin -- Typechecking superclasses of an instance declaration
| DerivOrigin -- Typechecking deriving
| StandAloneDerivOrigin -- Typechecking stand-alone deriving
instance Outputable InstOrigin where
ppr (OccurrenceOf name) = hsep [ptext SLIT("a use of"), quotes (ppr name)]
+ ppr (SpecPragOrigin name) = hsep [ptext SLIT("a specialisation pragma for"), quotes (ppr name)]
ppr (IPOccOrigin name) = hsep [ptext SLIT("a use of implicit parameter"), quotes (ppr name)]
ppr (IPBindOrigin name) = hsep [ptext SLIT("a binding for implicit parameter"), quotes (ppr name)]
ppr RecordUpdOrigin = ptext SLIT("a record update")
+ ppr ExprSigOrigin = ptext SLIT("an expression type signature")
+ ppr ViewPatOrigin = ptext SLIT("a view pattern")
ppr (LiteralOrigin lit) = hsep [ptext SLIT("the literal"), quotes (ppr lit)]
ppr (ArithSeqOrigin seq) = hsep [ptext SLIT("the arithmetic sequence"), quotes (ppr seq)]
ppr (PArrSeqOrigin seq) = hsep [ptext SLIT("the parallel array sequence"), quotes (ppr seq)]
- ppr InstSigOrigin = ptext SLIT("instantiating a type signature")
+ ppr TupleOrigin = ptext SLIT("a tuple")
+ ppr NegateOrigin = ptext SLIT("a use of syntactic negation")
ppr InstScOrigin = ptext SLIT("the superclasses of an instance declaration")
ppr DerivOrigin = ptext SLIT("the 'deriving' clause of a data type declaration")
ppr StandAloneDerivOrigin = ptext SLIT("a 'deriving' declaration")
ppr (ImplicOrigin doc) = doc
ppr (SigOrigin info) = pprSkolInfo info
ppr EqOrigin = ptext SLIT("a type equality")
-
\end{code}
projects / ghc-hetmet.git / blobdiff