Language.Haskell.Syntax.Type

This is used in the syntax. In constructor declaration. It must keep the arrow representation.

Denotes the type of arrows in the surface language

Haskell Type

Located Haskell Type

Haskell Kind

Located Haskell Kind

The type variable binders in an HsForAllTy. See also Note [Variable Specificity and Forall Visibility] in GHC.Tc.Gen.HsType.

Haskell Type Variable Binder The flag annotates the binder. It is Specificity in places where explicit specificity is allowed (e.g. x :: forall {a} b. ...) or () in other places.

Located Haskell Type Variable Binder

Located Haskell Quantified Type Variables

The outermost type variables in a type that obeys the forall-or-nothing rule. See Note [forall-or-nothing rule].

Used for type-family instance equations, e.g.,

type instance forall a. F [a] = Tree a

The notion of specificity is irrelevant in type family equations, so we use () for the HsOuterTyVarBndrs flag.

Used for signatures, e.g.,

f :: forall a {b}. blah

We use Specificity for the HsOuterTyVarBndrs flag to allow distinguishing between specified and inferred type variables.

Haskell Wildcard Binders

Types that can appear in pattern signatures, as well as the signatures for term-level binders in RULES. See Note [Pattern signature binders and scoping].

This is very similar to HsSigWcType, but with slightly different semantics: see Note [HsType binders]. See also Note [The wildcard story for types].

A type signature that obeys the forall-or-nothing rule. In other words, an LHsType that uses an HsOuterSigTyVarBndrs to represent its outermost type variable quantification. See Note [Representing type signatures].

Located Haskell Signature Type

Located Haskell Signature Wildcard Type

Located Haskell Wildcard Type

Haskell Tuple Sort

Haskell Context

Located Haskell Context

Haskell Type Literal

These names are used early on to store the names of implicit parameters. They completely disappear after type-checking.

Arguments in an expression/type after splitting

Located Bang Type

Bang Type

In the parser, strictness and packedness annotations bind more tightly than docstrings. This means that when consuming a BangType (and looking for HsBangTy) we must be ready to peer behind a potential layer of HsDocTy. See #15206 for motivation and getBangType for an example.

Haskell Source Bang

Bangs on data constructor arguments as the user wrote them in the source code.

(HsSrcBang _ SrcUnpack SrcLazy) and (HsSrcBang _ SrcUnpack NoSrcStrict) (without StrictData) makes no sense, we emit a warning (in checkValidDataCon) and treat it like (HsSrcBang _ NoSrcUnpack SrcLazy)

Is a TyCon a promoted data constructor or just a normal type constructor?

Constructor Declaration Field

Located Constructor Declaration Field

Describes the arguments to a data constructor. This is a common representation for several constructor-related concepts, including:

• The arguments in a Haskell98-style constructor declaration (see HsConDeclH98Details in GHC.Hs.Decls).

• The arguments in constructor patterns in case/function definitions (see HsConPatDetails in GHC.Hs.Pat).

• The left-hand side arguments in a pattern synonym binding (see HsPatSynDetails in GHC.Hs.Binds).

One notable exception is the arguments in a GADT constructor, which uses a separate data type entirely (see HsConDeclGADTDetails in GHC.Hs.Decls). This is because GADT constructors cannot be declared with infix syntax, unlike the concepts above (#18844).

An empty list that can be used to indicate that there are no type arguments allowed in cases where HsConDetails is applied to Void.

Field Occurrence

Represents an *occurrence* of a field. This may or may not be a binding occurrence (e.g. this type is used in ConDeclField and RecordPatSynField which bind their fields, but also in HsRecField for record construction and patterns, which do not).

We store both the RdrName the user originally wrote, and after the renamer we use the extension field to store the selector function.

Located Field Occurrence

Ambiguous Field Occurrence

Represents an *occurrence* of a field that is potentially ambiguous after the renamer, with the ambiguity resolved by the typechecker. We always store the RdrName that the user originally wrote, and store the selector function after the renamer (for unambiguous occurrences) or the typechecker (for ambiguous occurrences).

See Note [HsRecField and HsRecUpdField] in GHC.Hs.Pat. See Note [Located RdrNames] in GHC.Hs.Expr.

Located Ambiguous Field Occurrence

Does this HsTyVarBndr come with an explicit kind annotation?