ghc-7.0.3: The GHC API

CoreSyn

Contents

- Main data types
  - `Expr` construction
  - Simple `Expr` access functions and predicates
- Unfolding data types
  - Constructing `Unfolding`s
  - Predicates and deconstruction on `Unfolding`
- Strictness
- Annotated expression data types
  - Operations on annotated expressions
  - Operations on annotations
- Core rule data types
  - Operations on `CoreRule`s

Description

CoreSyn holds all the main data types for use by for the Glasgow Haskell Compiler midsection

Synopsis

- data Expr b
  - = Var Id
  - | Lit Literal
  - | App (Expr b) (Arg b)
  - | Lam b (Expr b)
  - | Let (Bind b) (Expr b)
  - | Case (Expr b) b Type [Alt b]
  - | Cast (Expr b) Coercion
  - | Note Note (Expr b)
  - | Type Type
- type Alt b = (AltCon, [b], Expr b)
- data Bind b
  - = NonRec b (Expr b)
  - | Rec [(b, Expr b)]
- data AltCon
  - = DataAlt DataCon
  - | LitAlt Literal
  - | DEFAULT
- type Arg b = Expr b
- data Note
  - = SCC CostCentre
  - | CoreNote String
- type CoreExpr = Expr CoreBndr
- type CoreAlt = Alt CoreBndr
- type CoreBind = Bind CoreBndr
- type CoreArg = Arg CoreBndr
- type CoreBndr = Var
- type TaggedExpr t = Expr (TaggedBndr t)
- type TaggedAlt t = Alt (TaggedBndr t)
- type TaggedBind t = Bind (TaggedBndr t)
- type TaggedArg t = Arg (TaggedBndr t)
- data TaggedBndr t = TB CoreBndr t
- mkLets :: [Bind b] -> Expr b -> Expr b
- mkLams :: [b] -> Expr b -> Expr b
- mkApps :: Expr b -> [Arg b] -> Expr b
- mkTyApps :: Expr b -> [Type] -> Expr b
- mkVarApps :: Expr b -> [Var] -> Expr b
- mkIntLit :: Integer -> Expr b
- mkIntLitInt :: Int -> Expr b
- mkWordLit :: Integer -> Expr b
- mkWordLitWord :: Word -> Expr b
- mkCharLit :: Char -> Expr b
- mkStringLit :: String -> Expr b
- mkFloatLit :: Rational -> Expr b
- mkFloatLitFloat :: Float -> Expr b
- mkDoubleLit :: Rational -> Expr b
- mkDoubleLitDouble :: Double -> Expr b
- mkConApp :: DataCon -> [Arg b] -> Expr b
- mkTyBind :: TyVar -> Type -> CoreBind
- varToCoreExpr :: CoreBndr -> Expr b
- varsToCoreExprs :: [CoreBndr] -> [Expr b]
- isTyCoVar :: Var -> Bool
- isId :: Var -> Bool
- cmpAltCon :: AltCon -> AltCon -> Ordering
- cmpAlt :: Alt b -> Alt b -> Ordering
- ltAlt :: Alt b -> Alt b -> Bool
- bindersOf :: Bind b -> [b]
- bindersOfBinds :: [Bind b] -> [b]
- rhssOfBind :: Bind b -> [Expr b]
- rhssOfAlts :: [Alt b] -> [Expr b]
- collectBinders :: Expr b -> ([b], Expr b)
- collectTyBinders :: CoreExpr -> ([TyVar], CoreExpr)
- collectValBinders :: CoreExpr -> ([Id], CoreExpr)
- collectTyAndValBinders :: CoreExpr -> ([TyVar], [Id], CoreExpr)
- collectArgs :: Expr b -> (Expr b, [Arg b])
- coreExprCc :: Expr b -> CostCentre
- flattenBinds :: [Bind b] -> [(b, Expr b)]
- isValArg :: Expr b -> Bool
- isTypeArg :: Expr b -> Bool
- valArgCount :: [Arg b] -> Int
- valBndrCount :: [CoreBndr] -> Int
- isRuntimeArg :: CoreExpr -> Bool
- isRuntimeVar :: Var -> Bool
- notSccNote :: Note -> Bool
- data Unfolding
  - = NoUnfolding
  - | OtherCon [AltCon]
  - | DFunUnfolding Arity DataCon [DFunArg CoreExpr]
  - | CoreUnfolding {
    - uf_tmpl :: CoreExpr
    - uf_src :: UnfoldingSource
    - uf_is_top :: Bool
    - uf_arity :: Arity
    - uf_is_value :: Bool
    - uf_is_conlike :: Bool
    - uf_is_cheap :: Bool
    - uf_expandable :: Bool
    - uf_guidance :: UnfoldingGuidance
    }
- data UnfoldingGuidance
  - = UnfWhen {
    - ug_unsat_ok :: Bool
    - ug_boring_ok :: Bool
    }
  - | UnfIfGoodArgs {
    - ug_args :: [Int]
    - ug_size :: Int
    - ug_res :: Int
    }
  - | UnfNever
- data UnfoldingSource
  - = InlineRhs
  - | InlineStable
  - | InlineCompulsory
  - | InlineWrapper Id
- data DFunArg e
  - = DFunPolyArg e
  - | DFunConstArg e
  - | DFunLamArg Int
- dfunArgExprs :: [DFunArg e] -> [e]
- noUnfolding :: Unfolding
- evaldUnfolding :: Unfolding
- mkOtherCon :: [AltCon] -> Unfolding
- unSaturatedOk :: Bool
- needSaturated :: Bool
- boringCxtOk :: Bool
- boringCxtNotOk :: Bool
- unfoldingTemplate :: Unfolding -> CoreExpr
- setUnfoldingTemplate :: Unfolding -> CoreExpr -> Unfolding
- expandUnfolding_maybe :: Unfolding -> Maybe CoreExpr
- maybeUnfoldingTemplate :: Unfolding -> Maybe CoreExpr
- otherCons :: Unfolding -> [AltCon]
- unfoldingArity :: Unfolding -> Arity
- isValueUnfolding :: Unfolding -> Bool
- isEvaldUnfolding :: Unfolding -> Bool
- isCheapUnfolding :: Unfolding -> Bool
- isExpandableUnfolding :: Unfolding -> Bool
- isConLikeUnfolding :: Unfolding -> Bool
- isCompulsoryUnfolding :: Unfolding -> Bool
- isStableUnfolding :: Unfolding -> Bool
- isStableCoreUnfolding_maybe :: Unfolding -> Maybe UnfoldingSource
- isClosedUnfolding :: Unfolding -> Bool
- hasSomeUnfolding :: Unfolding -> Bool
- canUnfold :: Unfolding -> Bool
- neverUnfoldGuidance :: UnfoldingGuidance -> Bool
- isStableSource :: UnfoldingSource -> Bool
- seqExpr :: CoreExpr -> ()
- seqExprs :: [CoreExpr] -> ()
- seqUnfolding :: Unfolding -> ()
- type AnnExpr bndr annot = (annot, AnnExpr' bndr annot)
- data AnnExpr' bndr annot
  - = AnnVar Id
  - | AnnLit Literal
  - | AnnLam bndr (AnnExpr bndr annot)
  - | AnnApp (AnnExpr bndr annot) (AnnExpr bndr annot)
  - | AnnCase (AnnExpr bndr annot) bndr Type [AnnAlt bndr annot]
  - | AnnLet (AnnBind bndr annot) (AnnExpr bndr annot)
  - | AnnCast (AnnExpr bndr annot) Coercion
  - | AnnNote Note (AnnExpr bndr annot)
  - | AnnType Type
- data AnnBind bndr annot
  - = AnnNonRec bndr (AnnExpr bndr annot)
  - | AnnRec [(bndr, AnnExpr bndr annot)]
- type AnnAlt bndr annot = (AltCon, [bndr], AnnExpr bndr annot)
- collectAnnArgs :: AnnExpr b a -> (AnnExpr b a, [AnnExpr b a])
- deAnnotate :: AnnExpr bndr annot -> Expr bndr
- deAnnotate' :: AnnExpr' bndr annot -> Expr bndr
- deAnnAlt :: AnnAlt bndr annot -> Alt bndr
- collectAnnBndrs :: AnnExpr bndr annot -> ([bndr], AnnExpr bndr annot)
- data CoreRule
  - = Rule {
    - ru_name :: RuleName
    - ru_act :: Activation
    - ru_fn :: Name
    - ru_rough :: [Maybe Name]
    - ru_bndrs :: [CoreBndr]
    - ru_args :: [CoreExpr]
    - ru_rhs :: CoreExpr
    - ru_auto :: Bool
    - ru_local :: Bool
    }
  - | BuiltinRule {
    - ru_name :: RuleName
    - ru_fn :: Name
    - ru_nargs :: Int
    - ru_try :: IdUnfoldingFun -> [CoreExpr] -> Maybe CoreExpr
    }
- type RuleName = FastString
- type IdUnfoldingFun = Id -> Unfolding
- seqRules :: [CoreRule] -> ()
- ruleArity :: CoreRule -> Int
- ruleName :: CoreRule -> RuleName
- ruleIdName :: CoreRule -> Name
- ruleActivation :: CoreRule -> Activation
- setRuleIdName :: Name -> CoreRule -> CoreRule
- isBuiltinRule :: CoreRule -> Bool
- isLocalRule :: CoreRule -> Bool

# Main data types

data Expr b

This is the data type that represents GHCs core intermediate language. Currently GHC uses System FC http://research.microsoft.com/~simonpj/papers/ext-f/ for this purpose, which is closely related to the simpler and better known System F http://en.wikipedia.org/wiki/System_F.

We get from Haskell source to this Core language in a number of stages:

1. The source code is parsed into an abstract syntax tree, which is represented by the data type `HsExpr.HsExpr` with the names being `RdrName.RdrNames`
2. This syntax tree is renamed, which attaches a `Unique.Unique` to every `RdrName.RdrName` (yielding a `Name`) to disambiguate identifiers which are lexically identical. For example, this program:

          f x = let f x = x + 1
                in f (x - 2)

Would be renamed by having `Unique`s attached so it looked something like this:

          f_1 x_2 = let f_3 x_4 = x_4 + 1
                    in f_3 (x_2 - 2)

1. The resulting syntax tree undergoes type checking (which also deals with instantiating type class arguments) to yield a `HsExpr.HsExpr` type that has `Id.Id` as it's names.
2. Finally the syntax tree is desugared from the expressive `HsExpr.HsExpr` type into this `Expr` type, which has far fewer constructors and hence is easier to perform optimization, analysis and code generation on.

The type parameter `b` is for the type of binders in the expression tree.

Constructors

Var Id | Variables
Lit Literal | Primitive literals
App (Expr b) (Arg b) | Applications: note that the argument may be a `Type`. See CoreSyn for another invariant
Lam b (Expr b) | Lambda abstraction

Let (Bind b) (Expr b)

Recursive and non recursive `let`s. Operationally this corresponds to allocating a thunk for the things bound and then executing the sub-expression.

The right hand sides of all top-level and recursive `let`s must be of lifted type (see Type for the meaning of lifted vs. unlifted).

The right hand side of of a non-recursive `Let` _and_ the argument of an `App`, may be of unlifted type, but only if the expression is ok-for-speculation. This means that the let can be floated around without difficulty. For example, this is OK:

     y::Int# = x +# 1#

But this is not, as it may affect termination if the expression is floated out:

     y::Int# = fac 4#

In this situation you should use `case` rather than a `let`. The function `CoreUtils.needsCaseBinding` can help you determine which to generate, or alternatively use `MkCore.mkCoreLet` rather than this constructor directly, which will generate a `case` if necessary

We allow a non-recursive let to bind a type variable, thus:

     Let (NonRec tv (Type ty)) body

This can be very convenient for postponing type substitutions until the next run of the simplifier.

At the moment, the rest of the compiler only deals with type-let in a Let expression, rather than at top level. We may want to revist this choice.

Case (Expr b) b Type [Alt b]

Case split. Operationally this corresponds to evaluating the scrutinee (expression examined) to weak head normal form and then examining at most one level of resulting constructor (i.e. you cannot do nested pattern matching directly with this).

The binder gets bound to the value of the scrutinee, and the `Type` must be that of all the case alternatives

This is one of the more complicated elements of the Core language, and comes with a number of restrictions:

The `DEFAULT` case alternative must be first in the list, if it occurs at all.

The remaining cases are in order of increasing tag (for `DataAlts`) or lit (for `LitAlts`). This makes finding the relevant constructor easy, and makes comparison easier too.

The list of alternatives must be exhaustive. An exhaustive case does not necessarily mention all constructors:

          data Foo = Red | Green | Blue
     ... case x of
          Red   -> True
          other -> f (case x of
                          Green -> ...
                          Blue  -> ... ) ...

The inner case does not need a `Red` alternative, because `x` can't be `Red` at that program point.

Cast (Expr b) Coercion | Cast an expression to a particular type. This is used to implement `newtype`s (a `newtype` constructor or destructor just becomes a `Cast` in Core) and GADTs.
Note Note (Expr b) | Notes. These allow general information to be added to expressions in the syntax tree
Type Type | A type: this should only show up at the top level of an Arg

Instances

Typeable1 Expr |
Data b => Data (Expr b) |
OutputableBndr b => Outputable (Expr b) |

type Alt b = (AltCon, [b], Expr b)

A case split alternative. Consists of the constructor leading to the alternative, the variables bound from the constructor, and the expression to be executed given that binding. The default alternative is `(DEFAULT, [], rhs)`

data Bind b

Binding, used for top level bindings in a module and local bindings in a `let`.

Constructors

NonRec b (Expr b) |
Rec [(b, Expr b)] |

Instances

Typeable1 Bind |
Data b => Data (Bind b) |
OutputableBndr b => Outputable (Bind b) |

data AltCon

A case alternative constructor (i.e. pattern match)

Constructors

DataAlt DataCon | A plain data constructor: `case e of { Foo x -> ... }`. Invariant: the `DataCon` is always from a `data` type, and never from a `newtype`
LitAlt Literal | A literal: `case e of { 1 -> ... }`
DEFAULT | Trivial alternative: `case e of { _ -> ... }`

Instances

Eq AltCon |
Data AltCon |
Ord AltCon |
Show AltCon |
Typeable AltCon |
Outputable AltCon |

type Arg b = Expr b

Type synonym for expressions that occur in function argument positions. Only `Arg` should contain a `Type` at top level, general `Expr` should not

data Note

Allows attaching extra information to points in expressions rather than e.g. identifiers.

Constructors

SCC CostCentre | A cost centre annotation for profiling
CoreNote String | A generic core annotation, propagated but not used by GHC

Instances

Data Note |
Typeable Note |

type CoreExpr = Expr CoreBndr

Expressions where binders are `CoreBndr`s

type CoreAlt = Alt CoreBndr

Case alternatives where binders are `CoreBndr`s

type CoreBind = Bind CoreBndr

Binding groups where binders are `CoreBndr`s

type CoreArg = Arg CoreBndr

Argument expressions where binders are `CoreBndr`s

type CoreBndr = Var

The common case for the type of binders and variables when we are manipulating the Core language within GHC

type TaggedExpr t = Expr (TaggedBndr t)

type TaggedAlt t = Alt (TaggedBndr t)

type TaggedBind t = Bind (TaggedBndr t)

type TaggedArg t = Arg (TaggedBndr t)

data TaggedBndr t

Binders are tagged with a t

Constructors

TB CoreBndr t |

Instances

Outputable b => OutputableBndr (TaggedBndr b) |
Outputable b => Outputable (TaggedBndr b) |

## `Expr` construction

mkLets :: [Bind b] -> Expr b -> Expr b

Bind all supplied binding groups over an expression in a nested let expression. Prefer to use `CoreUtils.mkCoreLets` if possible

mkLams :: [b] -> Expr b -> Expr b

Bind all supplied binders over an expression in a nested lambda expression. Prefer to use `CoreUtils.mkCoreLams` if possible

mkApps :: Expr b -> [Arg b] -> Expr b

Apply a list of argument expressions to a function expression in a nested fashion. Prefer to use `CoreUtils.mkCoreApps` if possible

mkTyApps :: Expr b -> [Type] -> Expr b

Apply a list of type argument expressions to a function expression in a nested fashion

mkVarApps :: Expr b -> [Var] -> Expr b

Apply a list of type or value variables to a function expression in a nested fashion

mkIntLit :: Integer -> Expr b

Create a machine integer literal expression of type `Int#` from an `Integer`. If you want an expression of type `Int` use `MkCore.mkIntExpr`

mkIntLitInt :: Int -> Expr b

Create a machine integer literal expression of type `Int#` from an `Int`. If you want an expression of type `Int` use `MkCore.mkIntExpr`

mkWordLit :: Integer -> Expr b

Create a machine word literal expression of type `Word#` from an `Integer`. If you want an expression of type `Word` use `MkCore.mkWordExpr`

mkWordLitWord :: Word -> Expr b

Create a machine word literal expression of type `Word#` from a `Word`. If you want an expression of type `Word` use `MkCore.mkWordExpr`

mkCharLit :: Char -> Expr b

Create a machine character literal expression of type `Char#`. If you want an expression of type `Char` use `MkCore.mkCharExpr`

mkStringLit :: String -> Expr b

Create a machine string literal expression of type `Addr#`. If you want an expression of type `String` use `MkCore.mkStringExpr`

mkFloatLit :: Rational -> Expr b

Create a machine single precision literal expression of type `Float#` from a `Rational`. If you want an expression of type `Float` use `MkCore.mkFloatExpr`

mkFloatLitFloat :: Float -> Expr b

Create a machine single precision literal expression of type `Float#` from a `Float`. If you want an expression of type `Float` use `MkCore.mkFloatExpr`

mkDoubleLit :: Rational -> Expr b

Create a machine double precision literal expression of type `Double#` from a `Rational`. If you want an expression of type `Double` use `MkCore.mkDoubleExpr`

mkDoubleLitDouble :: Double -> Expr b

Create a machine double precision literal expression of type `Double#` from a `Double`. If you want an expression of type `Double` use `MkCore.mkDoubleExpr`

mkConApp :: DataCon -> [Arg b] -> Expr b

Apply a list of argument expressions to a data constructor in a nested fashion. Prefer to use `MkCore.mkCoreConApps` if possible

mkTyBind :: TyVar -> Type -> CoreBind

Create a binding group where a type variable is bound to a type. Per CoreSyn, this can only be used to bind something in a non-recursive `let` expression

varToCoreExpr :: CoreBndr -> Expr b

Convert a binder into either a `Var` or `Type` `Expr` appropriately

varsToCoreExprs :: [CoreBndr] -> [Expr b]

isTyCoVar :: Var -> Bool

isId :: Var -> Bool

cmpAltCon :: AltCon -> AltCon -> Ordering

Compares `AltCon`s within a single list of alternatives

cmpAlt :: Alt b -> Alt b -> Ordering

ltAlt :: Alt b -> Alt b -> Bool

## Simple `Expr` access functions and predicates

bindersOf :: Bind b -> [b]

Extract every variable by this group

bindersOfBinds :: [Bind b] -> [b]

`bindersOf` applied to a list of binding groups

rhssOfBind :: Bind b -> [Expr b]

rhssOfAlts :: [Alt b] -> [Expr b]

collectBinders :: Expr b -> ([b], Expr b)

We often want to strip off leading lambdas before getting down to business. This function is your friend.

collectTyBinders :: CoreExpr -> ([TyVar], CoreExpr)

Collect as many type bindings as possible from the front of a nested lambda

collectValBinders :: CoreExpr -> ([Id], CoreExpr)

Collect as many value bindings as possible from the front of a nested lambda

collectTyAndValBinders :: CoreExpr -> ([TyVar], [Id], CoreExpr)

Collect type binders from the front of the lambda first, then follow up by collecting as many value bindings as possible from the resulting stripped expression

collectArgs :: Expr b -> (Expr b, [Arg b])

Takes a nested application expression and returns the the function being applied and the arguments to which it is applied

coreExprCc :: Expr b -> CostCentre

Gets the cost centre enclosing an expression, if any. It looks inside lambdas because `(scc "foo" \x.e) = \x. scc "foo" e`

flattenBinds :: [Bind b] -> [(b, Expr b)]

Collapse all the bindings in the supplied groups into a single list of lhs/rhs pairs suitable for binding in a `Rec` binding group

isValArg :: Expr b -> Bool

Returns `False` iff the expression is a `Type` expression at its top level

isTypeArg :: Expr b -> Bool

Returns `True` iff the expression is a `Type` expression at its top level

valArgCount :: [Arg b] -> Int

The number of argument expressions that are values rather than types at their top level

valBndrCount :: [CoreBndr] -> Int

The number of binders that bind values rather than types

isRuntimeArg :: CoreExpr -> Bool

Will this argument expression exist at runtime?

isRuntimeVar :: Var -> Bool

Will this variable exist at runtime?

notSccNote :: Note -> Bool

# Unfolding data types

data Unfolding

Records the unfolding of an identifier, which is approximately the form the identifier would have if we substituted its definition in for the identifier. This type should be treated as abstract everywhere except in CoreUnfold

Constructors

NoUnfolding | We have no information about the unfolding

OtherCon [AltCon]

It ain't one of these constructors. `OtherCon xs` also indicates that something has been evaluated and hence there's no point in re-evaluating it. `OtherCon []` is used even for non-data-type values to indicated evaluated-ness. Notably:

     data C = C !(Int -> Int)
     case x of { C f -> ... }

Here, `f` gets an `OtherCon []` unfolding.

DFunUnfolding Arity DataCon [DFunArg CoreExpr] |

CoreUnfolding

An unfolding with redundant cached information. Parameters:

uf_tmpl: Template used to perform unfolding; NB: Occurrence info is guaranteed correct: see Note [OccInfo in unfoldings and rules]

uf_is_top: Is this a top level binding?

uf_is_value: `exprIsHNF` template (cached); it is ok to discard a `seq` on this variable

uf_is_cheap: Does this waste only a little work if we expand it inside an inlining? Basically this is a cached version of `exprIsCheap`

uf_guidance: Tells us about the size of the unfolding template

Fields

uf_tmpl :: CoreExpr
uf_src :: UnfoldingSource
uf_is_top :: Bool
uf_arity :: Arity
uf_is_value :: Bool
uf_is_conlike :: Bool
uf_is_cheap :: Bool
uf_expandable :: Bool
uf_guidance :: UnfoldingGuidance

Instances

Outputable Unfolding |

data UnfoldingGuidance

`UnfoldingGuidance` says when unfolding should take place

Constructors

UnfWhen |

Fields

ug_unsat_ok :: Bool
ug_boring_ok :: Bool

UnfIfGoodArgs |

Fields

ug_args :: [Int]
ug_size :: Int
ug_res :: Int

UnfNever |

Instances

Outputable UnfoldingGuidance |

data UnfoldingSource

Constructors

InlineRhs |
InlineStable |
InlineCompulsory |
InlineWrapper Id |

Instances

Outputable UnfoldingSource |

data DFunArg e

Constructors

DFunPolyArg e |
DFunConstArg e |
DFunLamArg Int |

Instances

Functor DFunArg |
Outputable e => Outputable (DFunArg e) |
Binary (DFunArg IfaceExpr) |

dfunArgExprs :: [DFunArg e] -> [e]

## Constructing `Unfolding`s

noUnfolding :: Unfolding

There is no known `Unfolding`

evaldUnfolding :: Unfolding

This unfolding marks the associated thing as being evaluated

mkOtherCon :: [AltCon] -> Unfolding

unSaturatedOk :: Bool

needSaturated :: Bool

boringCxtOk :: Bool

boringCxtNotOk :: Bool

## Predicates and deconstruction on `Unfolding`

unfoldingTemplate :: Unfolding -> CoreExpr

Retrieves the template of an unfolding: panics if none is known

setUnfoldingTemplate :: Unfolding -> CoreExpr -> Unfolding

expandUnfolding_maybe :: Unfolding -> Maybe CoreExpr

maybeUnfoldingTemplate :: Unfolding -> Maybe CoreExpr

Retrieves the template of an unfolding if possible

otherCons :: Unfolding -> [AltCon]

The constructors that the unfolding could never be: returns `[]` if no information is available

unfoldingArity :: Unfolding -> Arity

isValueUnfolding :: Unfolding -> Bool

Determines if it is certainly the case that the unfolding will yield a value (something in HNF): returns `False` if unsure

isEvaldUnfolding :: Unfolding -> Bool

Determines if it possibly the case that the unfolding will yield a value. Unlike `isValueUnfolding` it returns `True` for `OtherCon`

isCheapUnfolding :: Unfolding -> Bool

Is the thing we will unfold into certainly cheap?

isExpandableUnfolding :: Unfolding -> Bool

isConLikeUnfolding :: Unfolding -> Bool

`True` if the unfolding is a constructor application, the application of a CONLIKE function or `OtherCon`

isCompulsoryUnfolding :: Unfolding -> Bool

isStableUnfolding :: Unfolding -> Bool

isStableCoreUnfolding_maybe :: Unfolding -> Maybe UnfoldingSource

isClosedUnfolding :: Unfolding -> Bool

hasSomeUnfolding :: Unfolding -> Bool

Only returns False if there is no unfolding information available at all

canUnfold :: Unfolding -> Bool

neverUnfoldGuidance :: UnfoldingGuidance -> Bool

isStableSource :: UnfoldingSource -> Bool

# Strictness

seqExpr :: CoreExpr -> ()

seqExprs :: [CoreExpr] -> ()

seqUnfolding :: Unfolding -> ()

# Annotated expression data types

type AnnExpr bndr annot = (annot, AnnExpr' bndr annot)

Annotated core: allows annotation at every node in the tree

data AnnExpr' bndr annot

A clone of the `Expr` type but allowing annotation at every tree node

Constructors

AnnVar Id |
AnnLit Literal |
AnnLam bndr (AnnExpr bndr annot) |
AnnApp (AnnExpr bndr annot) (AnnExpr bndr annot) |
AnnCase (AnnExpr bndr annot) bndr Type [AnnAlt bndr annot] |
AnnLet (AnnBind bndr annot) (AnnExpr bndr annot) |
AnnCast (AnnExpr bndr annot) Coercion |
AnnNote Note (AnnExpr bndr annot) |
AnnType Type |

data AnnBind bndr annot

A clone of the `Bind` type but allowing annotation at every tree node

Constructors

AnnNonRec bndr (AnnExpr bndr annot) |
AnnRec [(bndr, AnnExpr bndr annot)] |

type AnnAlt bndr annot = (AltCon, [bndr], AnnExpr bndr annot)

A clone of the `Alt` type but allowing annotation at every tree node

## Operations on annotated expressions

collectAnnArgs :: AnnExpr b a -> (AnnExpr b a, [AnnExpr b a])

Takes a nested application expression and returns the the function being applied and the arguments to which it is applied

## Operations on annotations

deAnnotate :: AnnExpr bndr annot -> Expr bndr

deAnnotate' :: AnnExpr' bndr annot -> Expr bndr

deAnnAlt :: AnnAlt bndr annot -> Alt bndr

collectAnnBndrs :: AnnExpr bndr annot -> ([bndr], AnnExpr bndr annot)

As `collectBinders` but for `AnnExpr` rather than `Expr`

# Core rule data types

data CoreRule

A `CoreRule` is:

- "Local" if the function it is a rule for is defined in the same module as the rule itself.
- "Orphan" if nothing on the LHS is defined in the same module as the rule itself

Constructors

Rule |

Fields

ru_name :: RuleName

  Name of the rule, for communication with the user

ru_act :: Activation

  When the rule is active

ru_fn :: Name

  Name of the `Id.Id` at the head of this rule

ru_rough :: [Maybe Name]

  Name at the head of each argument to the left hand side

ru_bndrs :: [CoreBndr]

  Variables quantified over

ru_args :: [CoreExpr]

  Left hand side arguments

ru_rhs :: CoreExpr

  Right hand side of the rule Occurrence info is guaranteed correct See Note [OccInfo in unfoldings and rules]

ru_auto :: Bool

  `True` = this rule is auto-generated `False` = generated at the users behest Main effect: reporting of orphan-hood

ru_local :: Bool

  `True` iff the fn at the head of the rule is defined in the same module as the rule and is not an implicit `Id` (like a record selector, class operation, or data constructor)

BuiltinRule | Built-in rules are used for constant folding and suchlike. They have no free variables.

Fields

ru_name :: RuleName

  Name of the rule, for communication with the user

ru_fn :: Name

  Name of the `Id.Id` at the head of this rule

ru_nargs :: Int

  Number of arguments that `ru_try` consumes, if it fires, including type arguments

ru_try :: IdUnfoldingFun -> [CoreExpr] -> Maybe CoreExpr

  This function does the rewrite. It given too many arguments, it simply discards them; the returned `CoreExpr` is just the rewrite of `ru_fn` applied to the first `ru_nargs` args

Instances

Outputable CoreRule |

type RuleName = FastString

type IdUnfoldingFun = Id -> Unfolding

## Operations on `CoreRule`s

seqRules :: [CoreRule] -> ()

ruleArity :: CoreRule -> Int

The number of arguments the `ru_fn` must be applied to before the rule can match on it

ruleName :: CoreRule -> RuleName

ruleIdName :: CoreRule -> Name

The `Name` of the `Id.Id` at the head of the rule left hand side

ruleActivation :: CoreRule -> Activation

setRuleIdName :: Name -> CoreRule -> CoreRule

Set the `Name` of the `Id.Id` at the head of the rule left hand side

isBuiltinRule :: CoreRule -> Bool

isLocalRule :: CoreRule -> Bool