ThStage(..), topStage, topSpliceStage,
ThLevel, impLevel, topLevel,
+ -- Arrows
+ ArrowCtxt(NoArrowCtxt), newArrowScope, escapeArrowScope,
+
-- Insts
Inst(..), InstOrigin(..), InstLoc(..), pprInstLoc,
instLocSrcLoc, instLocSrcSpan,
HscEnv, TypeEnv, TyThing,
GenAvailInfo(..), AvailInfo, HscSource(..),
availName, IsBootInterface, Deprecations )
-import Packages ( PackageId )
+import Packages ( PackageId, HomeModules )
import Type ( Type, TvSubstEnv, pprParendType, pprTyThingCategory )
import TcType ( TcTyVarSet, TcType, TcTauType, TcThetaType, SkolemInfo,
TcPredType, TcKind, tcCmpPred, tcCmpType, tcCmpTypes, pprSkolInfo )
-import InstEnv ( DFunId, InstEnv )
+import InstEnv ( Instance, InstEnv )
import IOEnv
import RdrName ( GlobalRdrEnv, LocalRdrEnv )
import Name ( Name )
-- from where, including things bound
-- in this module
+ tcg_home_mods :: HomeModules,
+ -- Calculated from ImportAvails, allows us to
+ -- call Packages.isHomeModule
+
tcg_dus :: DefUses, -- What is defined in this module and what is used.
-- The latter is used to generate
-- (a) version tracking; no need to recompile if these
-- tcg_inst_uses; the reference is implicit rather than explicit,
-- so we have to zap a mutable variable.
+ tcg_dfun_n :: TcRef Int, -- Allows us to number off the names of DFuns
+ -- It's convenient to allocate an External Name for a DFun, with
+ -- a permanently-fixed unique, just like other top-level functions
+ -- defined in this module. But that means we need a canonical
+ -- occurrence name, distinct from all other dfuns in this module,
+ -- and this name supply serves that purpose (df1, df2, etc).
+
+ -- The next fields accumulate the payload of the module
+ -- The binds, rules and foreign-decl fiels are collected
+ -- initially in un-zonked form and are finally zonked in tcRnSrcDecls
+
-- The next fields accumulate the payload of the
-- module The binds, rules and foreign-decl fiels are
-- collected initially in un-zonked form and are
tcg_binds :: LHsBinds Id, -- Value bindings in this module
tcg_deprecs :: Deprecations, -- ...Deprecations
- tcg_insts :: [DFunId], -- ...Instances
+ tcg_insts :: [Instance], -- ...Instances
tcg_rules :: [LRuleDecl Id], -- ...Rules
tcg_fords :: [LForeignDecl Id] -- ...Foreign import & exports
}
tcl_errs :: TcRef Messages, -- Place to accumulate errors
tcl_th_ctxt :: ThStage, -- Template Haskell context
+ tcl_arrow_ctxt :: ArrowCtxt, -- Arrow-notation context
tcl_rdr :: LocalRdrEnv, -- Local name envt
-- Maintained during renaming, of course, but also during
topStage = Comp
topSpliceStage = Splice (topLevel - 1) -- Stage for the body of a top-level splice
+---------------------------
+-- Arrow-notation context
+---------------------------
+
+{-
+In arrow notation, a variable bound by a proc (or enclosed let/kappa)
+is not in scope to the left of an arrow tail (-<) or the head of (|..|).
+For example
+
+ proc x -> (e1 -< e2)
+
+Here, x is not in scope in e1, but it is in scope in e2. This can get
+a bit complicated:
+
+ let x = 3 in
+ proc y -> (proc z -> e1) -< e2
+
+Here, x and z are in scope in e1, but y is not. We implement this by
+recording the environment when passing a proc (using newArrowScope),
+and returning to that (using escapeArrowScope) on the left of -< and the
+head of (|..|).
+-}
+
+data ArrowCtxt
+ = NoArrowCtxt
+ | ArrowCtxt (Env TcGblEnv TcLclEnv)
+
+-- Record the current environment (outside a proc)
+newArrowScope :: TcM a -> TcM a
+newArrowScope
+ = updEnv $ \env ->
+ env { env_lcl = (env_lcl env) { tcl_arrow_ctxt = ArrowCtxt env } }
+
+-- Return to the stored environment (from the enclosing proc)
+escapeArrowScope :: TcM a -> TcM a
+escapeArrowScope
+ = updEnv $ \ env -> case tcl_arrow_ctxt (env_lcl env) of
+ NoArrowCtxt -> env
+ ArrowCtxt env' -> env'
---------------------------
-- TcTyThing
-- So the starting point is all things that are in scope as 'M.x',
-- which is what this field tells us.
- imp_mods :: ModuleEnv (Module, Maybe Bool, SrcSpan),
+ imp_mods :: ModuleEnv (Module, Bool, SrcSpan),
-- Domain is all directly-imported modules
- -- Maybe value answers the question "is the import restricted?"
- -- Nothing => unrestricted import (e.g., "import Foo")
- -- Just True => restricted import, at least one entity (e.g., "import Foo(x)")
- -- Just False => fully restricted import (e.g., "import Foo ()")
- --
- -- A distinction is made between the first and the third in order
- -- to more precisely emit warnings about unused imports.
+ -- Bool means:
+ -- True => import was "import Foo ()"
+ -- False => import was some other form
--
-- We need the Module in the range because we can't get
-- the keys of a ModuleEnv
-- Used
-- (a) to help construct the usage information in
- -- the interface file; if we import everything we
- -- need to recompile if the module version changes
+ -- the interface file; if we import somethign we
+ -- need to recompile if the export version changes
-- (b) to specify what child modules to initialise
imp_dep_mods :: ModuleEnv (Module, IsBootInterface),
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