Module AbstractCurry.Types

This library contains a definition for representing Curry programs in Curry.

Note this defines a slightly new format for AbstractCurry in comparison to the first proposal of 2003.

Assumption: an abstract Curry program is stored in file with extension .acy

Author: Michael Hanus, Bjoern Peemoeller, Finn Teegen

Version: November 2020

Summary of exported operations:

version :: String   
Current version of AbstractCurry
preludeName :: String   
The name of the standard prelude.
pre :: String -> (String,String)   
Converts a string into a qualified name of the Prelude.

Exported datatypes:


MName

A module name.

Type synonym: MName = String


QName

The data type for representing qualified names. In AbstractCurry 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. An exception are locally defined names where the module name is the empty string (to avoid name clashes with a globally defined name).

Type synonym: QName = (MName,String)


CVisibility

Data type to specify the visibility of various entities.

Constructors:

  • Public :: CVisibility
  • Private :: CVisibility

CurryProg

Data type for representing a Curry module in the intermediate form. A value of this data type has the form

(CurryProg modname imports dfltdecl clsdecls instdecls typedecls
           funcdecls opdecls)

where modname: name of this module, imports: list of modules names that are imported, dfltdecl: optional default declaration clsdecls: Class declarations instdecls: Instance declarations typedecls: Type declarations functions: Function declarations opdecls: Operator precedence declarations

Constructors:


CDefaultDecl

Data type for representing default declarations.

Constructors:

  • CDefaultDecl :: [CTypeExpr] -> CDefaultDecl

CClassDecl

Data type for representing classes declarations.

A type class definition of the form

class cx => c a where { ...;f :: t;... }

is represented by the Curry term

(CClass c v cx tv [...(CFunc f ar v t [...,CRule r,...])...])

where tv is the index of the type variable a and v is the visibility of the type class resp. method. Note: The type variable indices are unique inside each class declaration and are usually numbered from 0. The methods' types share the type class' type variable index as the class variable has to occur in a method's type signature. The list of rules for a method's declaration may be empty if no default implementation is provided. The arity ar is determined by a given default implementation or 0. Regardless of whether typed or untyped abstract curry is generated, the methods' declarations are always typed.

Constructors:


CInstanceDecl

Data type for representing instance declarations.

An instance definition of the form

instance cx => c ty where { ...;fundecl;... }

is represented by the Curry term

(CInstance c cx ty [...fundecl...])

Note: The type variable indices are unique inside each instance declaration and are usually numbered from 0. The methods' types use the instance's type variable indices (if typed abstract curry is generated).

Constructors:


CTypeDecl

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 |...
  deriving (d1,...,dp)

is represented by the Curry term

(CType t v [i1,...,in]
       [...(CCons c v [t1,...,tkc])...] [d1,...,dp]))

where each ij is the index of the type variable xj and v is the visibility of the type resp. constructor.

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:


CTVarIName

The type for representing type variables. They are represented by (i,n) where i is a type variable index which is unique inside a function and n is a name (if possible, the name written in the source program).

Type synonym: CTVarIName = (Int,String)


CConsDecl

A constructor declaration consists of the name of the constructor and a list of the argument types of the constructor. The arity equals the number of types.

Constructors:


CFieldDecl

A record field declaration consists of the name of the the label, the visibility and its corresponding type.

Constructors:


CConstraint

Class constraint.

Type synonym: CConstraint = (QName,CTypeExpr)


CContext

Context.

Constructors:


CTypeExpr

Type expression. 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:


CQualTypeExpr

Qualified type expression.

Constructors:


CField

Labeled record fields

Type synonym: CField a = (QName,a)


COpDecl

Data type for operator declarations. An operator declaration "fix p n" in Curry corresponds to the AbstractCurry term (COp n fix p).

Constructors:


CFixity

Data type for operator associativity

Constructors:

  • CInfixOp :: CFixity
  • CInfixlOp :: CFixity
  • CInfixrOp :: CFixity

Arity

Function arity

Type synonym: Arity = Int


CFuncDecl

Data type for representing function declarations.

A function declaration in AbstractCurry is a term of the form

(CFunc name arity visibility type (CRules eval [CRule rule1,...,rulek]))

and represents the function name defined by the rules rule1,...,rulek.

Note: the variable indices are unique inside each rule

Thus, a function declaration consists of the name, arity, type, and a list of rules. The type is the function's type inferred by the type checker. However, if an AbstractCurry program is read with the operation AbstractCurry.Files.readUntypedCurry, the type is either the type signature provided by the programmer or the expression (CTCons ("Prelude","untyped") if the programmer has not provided an explicit type signature.

A function declaration with the constructor CmtFunc is similarly to CFunc but has a comment as an additional first argument. This comment could be used by pretty printers that generate a readable Curry program containing documentation comments.

Constructors:


CRule

The general form of a function rule. It consists of a list of patterns (left-hand side) and the right-hand side for these patterns.

Constructors:


CRhs

Right-hand-side of a CRule or a case expression. It is either a simple unconditional right-hand side or a list of guards with their corresponding right-hand sides, and a list of local declarations.

Constructors:


CLocalDecl

Data type for representing local (let/where) declarations

Constructors:


CVarIName

Data types for representing object variables. Object variables occurring in expressions are represented by (Var i) where i is a variable index.

Type synonym: CVarIName = (Int,String)


CPattern

Data type for representing pattern expressions.

Constructors:


CExpr

Data type for representing Curry expressions.

Constructors:


CLiteral

Data type for representing literals occurring in an expression. It is either an integer, a float, or a character constant.

Constructors:

  • CIntc :: Int -> CLiteral
  • CFloatc :: Float -> CLiteral
  • CCharc :: Char -> CLiteral
  • CStringc :: String -> CLiteral

CStatement

Data type for representing statements in do expressions and list comprehensions.

Constructors:


CCaseType

Type of case expressions

Constructors:

  • CRigid :: CCaseType
  • CFlex :: CCaseType

Exported operations:

version :: String   

Current version of AbstractCurry

Further infos:
  • solution complete, i.e., able to compute all solutions

preludeName :: String   

The name of the standard prelude.

Further infos:
  • solution complete, i.e., able to compute all solutions

pre :: String -> (String,String)   

Converts a string into a qualified name of the Prelude.

Further infos:
  • solution complete, i.e., able to compute all solutions