Language.Haskell.Syntax.Binds

Haskell Value Bindings

Haskell Implicit Parameter Bindings

Empty Local Bindings

Value Bindings In

Before renaming RHS; idR is always RdrName Not dependency analysed Recursive by default

Value Bindings Out

After renaming RHS; idR can be Name or Id Dependency analysed, later bindings in the list may depend on earlier ones.

Function-like Binding

FunBind is used for both functions f x = e and variables f = x -> e and strict variables !x = x + 1

Reason 1: Special case for type inference: see GHC.Tc.Gen.Bind.tcMonoBinds.

Reason 2: Instance decls can only have FunBinds, which is convenient. If you change this, you'll need to change e.g. rnMethodBinds

But note that the form f :: a->a = ... parses as a pattern binding, just like (f :: a -> a) = ...

Strict bindings have their strictness recorded in the SrcStrictness of their MatchContext. See Note [FunBind vs PatBind] for details about the relationship between FunBind and PatBind.

Pattern Binding

The pattern is never a simple variable; That case is done by FunBind. See Note [FunBind vs PatBind] for details about the relationship between FunBind and PatBind.

Variable Binding

Dictionary binding and suchlike. All VarBinds are introduced by the type checker

Patterns Synonym Binding

An ordinary type signature

f :: Num a => a -> a

After renaming, this list of Names contains the named wildcards brought into scope by this signature. For a signature _ -> _a -> Bool, the renamer will leave the unnamed wildcard _ untouched, and the named wildcard _a is then replaced with fresh meta vars in the type. Their names are stored in the type signature that brought them into scope, in this third field to be more specific.

A pattern synonym type signature

pattern Single :: () => (Show a) => a -> [a]

A signature for a class method False: ordinary class-method signature True: generic-default class method signature e.g. class C a where op :: a -> a -- Ordinary default op :: Eq a => a -> a -- Generic default No wildcards allowed here

An ordinary fixity declaration

    infixl 8 ***

An inline pragma

{#- INLINE f #-}

An old-form specialisation pragma

{-# SPECIALISE f :: Int -> Int #-}

NB: this constructor is deprecated and will be removed in GHC 9.18 (#25540)

A new-form specialisation pragma (see GHC Proposal #493) e.g. {-# SPECIALISE f @Int 1 :: Int -> Int #-} See Note [Overview of SPECIALISE pragmas]

A specialisation pragma for instance declarations only

{-# SPECIALISE instance Eq [Int] #-}

(Class tys); should be a specialisation of the current instance declaration

A minimal complete definition pragma

{-# MINIMAL a | (b, c | (d | e)) #-}

A "set cost centre" pragma for declarations

{-# SCC funName #-}

or

{-# SCC funName "cost_centre_name" #-}

A complete match pragma

{-# COMPLETE C, D [:: T] #-}

Used to inform the pattern match checker about additional complete matchings which, for example, arise from pattern synonym definitions.

• GHC.Parser.Annotation.AnnKeywordId : GHC.Parser.Annotation.AnnOpen, GHC.Parser.Annotation.AnnDcolon,GHC.Parser.Annotation.AnnClose