GHC uses several kinds of name internally:
- OccName.OccName: see OccName
- RdrName is the type of names that come directly from the parser. They
have not yet had their scoping and binding resolved by the renamer and can be
thought of to a first approximation as an OccName.OccName with an optional module
- Name: see Name
- Id.Id: see Id
- Var.Var: see Var
|The main type
|Do not use the data constructors of RdrName directly: prefer the family
of functions that creates them, such as mkRdrUnqual
|Unqual OccName||Used for ordinary, unqualified occurrences, e.g. x, y or Foo.
Create such a RdrName with mkRdrUnqual
|Qual ModuleName OccName||A qualified name written by the user in
source code. The module isn't necessarily
the module where the thing is defined;
just the one from which it is imported.
Examples are Bar.x, Bar.y or Bar.Foo.
Create such a RdrName with mkRdrQual
|Orig Module OccName||An original name; the module is the defining module.
This is used when GHC generates code that will be fed
into the renamer (e.g. from deriving clauses), but where
we want to say "Use Prelude.map dammit". One of these
can be created with mkOrig
We know exactly the Name. This is used:
- When the parser parses built-in syntax like 
and (,), but wants a RdrName from it
- By Template Haskell, when TH has generated a unique name
Such a RdrName can be created by using getRdrName on a Name
|Make a qualified RdrName in the given namespace and where the ModuleName and
the OccName are taken from the first and second elements of the tuple respectively
|Produce an original RdrName whose module that of a parent Name but its OccName
is derived from that of it's parent using the supplied function
This rather gruesome function is used mainly by the parser.
data T a = T | T1 Int
we parse the data constructors as types because of parser ambiguities,
so then we need to change the type constr to a data constr
The exact-name case can occur when parsing:
data  a =  | a : [a]
For the exact-name case we return an original name.
|Local mapping of RdrName to Name
|This environment is used to store local bindings (let, where, lambda, case).
It is keyed by OccName, because we never use it for qualified names
|Global mapping of RdrName to GlobalRdrElts
Keyed by OccName; when looking up a qualified name
we look up the OccName part, and then check the Provenance
to see if the appropriate qualification is valid. This
saves routinely doubling the size of the env by adding both
qualified and unqualified names to the domain.
The list in the codomain is required because there may be name clashes
These only get reported on lookup, not on construction
INVARIANT: All the members of the list have distinct
gre_name fields; that is, no duplicate Names
INVARIANT: Imported provenance => Name is an ExternalName
However LocalDefs can have an InternalName. This
happens only when type-checking a [d| ... |] Template
Haskell quotation; see this note in RnNames
Note [Top-level Names in Template Haskell decl quotes]
Hide any unqualified bindings for the specified OccNames
This is used in TH, when renaming a declaration bracket
[d| foo = ... |]
We want unqualified foo in ... to mean this foo, not
the one from the enclosing module. But the qualified name
from the enclosing module must certainly still be available
|For each OccName, see if there are multiple local definitions
for it. If so, remove all but one (to suppress subsequent error messages)
and return a list of the duplicate bindings
Take a list of GREs which have the right OccName
Pick those GREs that are suitable for this RdrName
And for those, keep only only the Provenances that are suitable
module A ( f ) where
import qualified Foo( f )
import Baz( f )
f = undefined
Let's suppose that Foo.f and Baz.f are the same entity really.
The export of f is ambiguous because it's in scope from the local def
and the import. The lookup of Unqual f should return a GRE for
the locally-defined f, and a GRE for the imported f, with a single
provenance, namely the one for Baz(f).
|Global RdrName mapping elements: GlobalRdrElt, Provenance, ImportSpec
|Test if an unqualifed version of this thing would be in scope
|Is in scope qualified with the given module?
|Is in scope unqualified?
|The Provenance of something says how it came to be in scope.
It's quite elaborate so that we can give accurate unused-name warnings.
|LocalDef||The thing was defined locally
The thing was imported.
INVARIANT: the list of ImportSpec is non-empty
|Print out the place where the name was imported
|The children of a Name are the things that are abbreviated by the ..
notation in export lists. Specifically:
TyCon Children are * data constructors
* record field ids
Class Children are * class operations
Each child has the parent thing as its Parent
|Describes a particular import declaration and is
shared among all the Provenances for that decl
|is_mod :: ModuleName||Module imported, e.g. import Muggle
Note the Muggle may well not be
the defining module for this thing!
|is_as :: ModuleName||Import alias, e.g. from as M (or Muggle if there is no as clause)
|is_qual :: Bool||Was this import qualified?
|is_dloc :: SrcSpan||The location of the entire import declaration
|Describes import info a particular Name
|ImpAll||The import had no import list,
or had a hiding list
The import had an import list.
The is_explicit field is True iff the thing was named
explicitly in the import specs rather
than being imported as part of a ... group. Consider:
import C( T(..) )
Here the constructors of T are not named explicitly;
only T is named explicitly.
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