This library supports metaprogramming, i.e., the manipulation of Curry programs in Curry. For this purpose, the library contains definitions of data types for the representation of Curry programs in the FlatCurry format where all function definitions are at the toplevel and pattern matching is replaced by case expressions and disjunctions.
Author: Michael Hanus
Version: July 2016
showQNameInModule
:: String > (String,String) > String
Shows a qualified type name as a name relative to a module (first argument). 
showQName
:: (String,String) > String
Shows a qualified name. 
Data type for representing a Curry module in the intermediate form. A value of this data type has the form
(Prog modname imports typedecls functions opdecls)
where
modname
is the name of this module,
imports
is the list of modules names that are imported, and
typedecls
, functions
, and opdecls
are the list of
data type, function, and operator declarations
contained in this module, respectively.
Constructors:
The data type for representing qualified names. In FlatCurry all names are qualified to avoid name clashes. The first component is the module name and the second component the unqualified name as it occurs in the source program.
Type synonym: QName = (String,String)
Data type to specify the visibility of various entities.
Constructors:
Public
:: Visibility
Private
:: Visibility
The data type for representing type variables.
They are represented by (TVar i)
where i
is a type variable index.
Type synonym: TVarIndex = Int
Kinded type variables are represented by a tuple of type variable index and kind.
Type synonym: TVarWithKind = (TVarIndex,Kind)
Data type for representing definitions of algebraic data types and type synonyms.
A data type definition of the form
data t x1...xn = ... c t1....tkc ...
is represented by the FlatCurry term
(Type t [i1,...,in] [...(Cons c kc [t1,...,tkc])...])
where each ij
is the index of the type variable xj
.
Note: the type variable indices are unique inside each type declaration and are usually numbered from 0
Thus, a data type declaration consists of the name of the data type, a list of type parameters and a list of constructor declarations.
Constructors:
Type
:: QName > Visibility > [TVarWithKind] > [ConsDecl] > TypeDecl
TypeSyn
:: QName > Visibility > [TVarWithKind] > TypeExpr > TypeDecl
TypeNew
:: QName > Visibility > [TVarWithKind] > NewConsDecl > TypeDecl
A constructor declaration consists of the name and arity of the constructor and a list of the argument types of the constructor.
Constructors:
Cons
:: QName > Int > Visibility > [TypeExpr] > ConsDecl
A constructor declaration for a newtype consists of the name of the constructor and the argument type of the constructor.
Constructors:
NewCons
:: QName > Visibility > TypeExpr > NewConsDecl
Data type for type expressions. A type expression is either a type variable, a function type, or a type constructor application.
Note: the names of the predefined type constructors are "Int", "Float", "Bool", "Char", "IO", "()" (unit type), "(,...,)" (tuple types), "[]" (list type)
Constructors:
TVar
:: TVarIndex > TypeExpr
FuncType
:: TypeExpr > TypeExpr > TypeExpr
TCons
:: QName > [TypeExpr] > TypeExpr
ForallType
:: [TVarWithKind] > TypeExpr > TypeExpr
Constructors:
Data type for operator declarations.
An operator declaration fix p n
in Curry corresponds to the
FlatCurry term (Op n fix p)
.
Constructors:
Data types for the different choices for the fixity of an operator.
Constructors:
InfixOp
:: Fixity
InfixlOp
:: Fixity
InfixrOp
:: Fixity
Data type for representing object variables.
Object variables occurring in expressions are represented by (Var i)
where i
is a variable index.
Type synonym: VarIndex = Int
Arity of a function.
Type synonym: Arity = Int
Data type for representing function declarations.
A function declaration in FlatCurry is a term of the form
(Func name k type (Rule [i1,...,ik] e))
and represents the function name
with definition
name :: type name x1...xk = e
where each ij
is the index of the variable xj
.
Note: the variable indices are unique inside each function declaration and are usually numbered from 0
External functions are represented as
(Func name arity type (External s))
where s is the external name associated to this function.
Thus, a function declaration consists of the name, arity, type, and rule.
Constructors:
Func
:: QName > Arity > Visibility > TypeExpr > Rule > FuncDecl
A rule is either a list of formal parameters together with an expression or an "External" tag.
Constructors:
Data type for classifying case expressions. Case expressions can be either flexible or rigid in Curry.
Constructors:
Rigid
:: CaseType
Flex
:: CaseType
Data type for classifying combinations (i.e., a function/constructor applied to some arguments).
Constructors:
FuncCall
:: CombType
: a call to a function where all arguments are provided
ConsCall
:: CombType
: a call with a constructor at the top, all arguments are provided
FuncPartCall
:: Arity > CombType
: a partial call to a function (i.e., not all arguments
are provided) where the parameter is the number of
missing arguments
ConsPartCall
:: Arity > CombType
: a partial call to a constructor (i.e., not all arguments
are provided) where the parameter is the number of
missing arguments
Data type for representing expressions.
Remarks:
ifthenelse expressions are represented as rigid case expressions:
(if e1 then e2 else e3)
is represented as
(case e1 of { True > e2; False > e3})
Higherorder applications are represented as calls to the (external)
function apply
. For instance, the rule
app f x = f x
is represented as
(Rule [0,1] (Comb FuncCall ("Prelude","apply") [Var 0, Var 1]))
A conditional rule is represented as a call to an external function
cond
where the first argument is the condition (a constraint).
For instance, the rule
equal2 x  x=:=2 = True
is represented as
(Rule [0] (Comb FuncCall ("Prelude","cond") [Comb FuncCall ("Prelude","=:=") [Var 0, Lit (Intc 2)], Comb FuncCall ("Prelude","True") []]))
Constructors:
Var
:: VarIndex > Expr
: variable (represented by unique index)
Lit
:: Literal > Expr
: literal (Int/Float/Char constant)
Comb
:: CombType > QName > [Expr] > Expr
: application (f e1 ... en)
of function/constructor f
with n
<=arity(f
)
Let
:: [(VarIndex,Expr)] > Expr > Expr
: introduction of local variables via (recursive) let declarations
Free
:: [VarIndex] > Expr > Expr
: introduction of free local variables
Or
:: Expr > Expr > Expr
: disjunction of two expressions (used to translate rules
with overlapping lefthand sides)
Case
:: CaseType > Expr > [BranchExpr] > Expr
: case distinction (rigid or flex)
Typed
:: Expr > TypeExpr > Expr
: typed expression to represent an expression with a
type declaration
Data type for representing branches in a case expression.
Branches "(m.c x1...xn) > e" in case expressions are represented as
(Branch (Pattern (m,c) [i1,...,in]) e)
where each ij
is the index of the pattern variable xj
, or as
(Branch (LPattern (Intc i)) e)
for integers as branch patterns (similarly for other literals like float or character constants).
Constructors:
Data type for representing patterns in case expressions.
Constructors:
Data type for representing literals occurring in an expression or case branch. It is either an integer, a float, or a character constant.
Constructors:
Intc
:: Int > Literal
Floatc
:: Float > Literal
Charc
:: Char > Literal
Shows a qualified type name as a name relative to a module (first argument). Thus, names not defined in this module (except for names defined in the prelude) are prefixed with their module name. 
Shows a qualified name.
