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 Uniques 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.

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)

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

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

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

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

Expressions where binders are CoreBndrs

Case alternatives where binders are CoreBndrs

Binding groups where binders are CoreBndrs

Argument expressions where binders are CoreBndrs

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

Binders are tagged with a t

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Convert a binder into either a Var or Type Expr appropriately

Compares AltCons within a single list of alternatives

Extract every variable by this group

bindersOf applied to a list of binding groups

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

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

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

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

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

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

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

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

Returns True iff the expression is a Type expression at its top level. Note this does NOT include Coercions.

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

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

The number of binders that bind values rather than types

Will this argument expression exist at runtime?

Will this variable exist at runtime?

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

UnfoldingGuidance says when unfolding should take place

There is no known Unfolding

This unfolding marks the associated thing as being evaluated

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

Retrieves the template of an unfolding if possible

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

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

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

Is the thing we will unfold into certainly cheap?

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

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

Annotated core: allows annotation at every node in the tree

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

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

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

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

As collectBinders but for AnnExpr rather than Expr

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

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

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

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