Language.Haskell.Syntax.Type

Denotes a function arrow, which could be -> or ⊸ or ::. :: counts as an "arrow" for these purposes, because in HsConDeclField we need to support both

data T where MkT :: Int -> Bool -> T
data T where MkT :: { x :: Int, y :: Bool } -> T

Denotes function arrows with optional modifiers attached.

The mult type argument is usually `LHsType (NoGhcTc pass)`, but when the annotation is part of a type used in a term, it is `LHsExpr pass`. See Note [Types in terms].

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 See Note [Type variable binders]

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

Modifier. Usually a modifier holds an LHsType, but inside expressions, it has an LHsExpr. See Note [Overview of Modifiers].

Located Modifier

Haskell 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

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

Constructor Declaration Record Field

Located Constructor Declaration Record 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).

Constructor declaration field specification, see Note [HsConDeclField on pass]

Field Occurrence

Represents an *occurrence* of a field. This may or may not be a binding occurrence (e.g. this type is used in HsConDeclRecField 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. See note [FieldOcc pass]

There is a wrinkle in that update field occurances are sometimes ambiguous during the rename stage. See note [Ambiguous FieldOcc in record updates] to see how we currently handle this.

Located Field Occurrence

Does this HsTyVarBndr come with an explicit kind annotation?