Module AbstractCurry.Types

Exported datatypes:

A module name.

Type synonym: MName = String

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)

Data type to specify the visibility of various entities.

Constructors:

• Public :: CVisibility
• Private :: CVisibility

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:

• CurryProg :: MName -> [MName] -> (Maybe CDefaultDecl) -> [CClassDecl] -> [CInstanceDecl] -> [CTypeDecl] -> [CFuncDecl] -> [COpDecl] -> CurryProg

Data type for representing default declarations.

Constructors:

• CDefaultDecl :: [CTypeExpr] -> CDefaultDecl

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:

• CClass :: QName -> CVisibility -> CContext -> CTVarIName -> [CFuncDecl] -> CClassDecl

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:

• CInstance :: QName -> CContext -> CTypeExpr -> [CFuncDecl] -> CInstanceDecl

Data type for representing definitions of algebraic data types and type synonyms.

A data type definition of the form

data t x1...xn = ...| forall y1...ym . cx => c t1....tkc |...
  deriving (d1,...,dp)

is represented by the Curry term

(CType t v [i1,...,in]
       [...(CCons [l1,...,lm] cx c kc v [t1,...,tkc])...] [d1,...,dp]))

where each ij is the index of the type variable xj, each lj is the index of the existentially quantified type variable yj 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:

• CType :: QName -> CVisibility -> [CTVarIName] -> [CConsDecl] -> [QName] -> CTypeDecl
• CTypeSyn :: QName -> CVisibility -> [CTVarIName] -> CTypeExpr -> CTypeDecl
• CNewType :: QName -> CVisibility -> [CTVarIName] -> CConsDecl -> [QName] -> CTypeDecl

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)

A constructor declaration consists of a list of existentially quantified type variables, a context, the name of the constructor and a list of the argument types of the constructor. The arity equals the number of types.

Constructors:

• CCons :: [CTVarIName] -> CContext -> QName -> CVisibility -> [CTypeExpr] -> CConsDecl
• CRecord :: [CTVarIName] -> CContext -> QName -> CVisibility -> [CFieldDecl] -> CConsDecl

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

Constructors:

• CField :: QName -> CVisibility -> CTypeExpr -> CFieldDecl

Class constraint.

Type synonym: CConstraint = (QName,CTypeExpr)

Context.

Constructors:

• CContext :: [CConstraint] -> CContext

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:

• CTVar :: CTVarIName -> CTypeExpr
• CFuncType :: CTypeExpr -> CTypeExpr -> CTypeExpr
• CTCons :: QName -> CTypeExpr
• CTApply :: CTypeExpr -> CTypeExpr -> CTypeExpr

Qualified type expression.

Constructors:

• CQualType :: CContext -> CTypeExpr -> CQualTypeExpr

Labeled record fields

Type synonym: CField a = (QName,a)

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

Constructors:

• COp :: QName -> CFixity -> Int -> COpDecl

Data type for operator associativity

Constructors:

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

Function arity

Type synonym: Arity = Int

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:

• CFunc :: QName -> Arity -> CVisibility -> CQualTypeExpr -> [CRule] -> CFuncDecl
• CmtFunc :: String -> QName -> Arity -> CVisibility -> CQualTypeExpr -> [CRule] -> CFuncDecl

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:

• CRule :: [CPattern] -> CRhs -> CRule

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:

• CSimpleRhs :: CExpr -> [CLocalDecl] -> CRhs
• CGuardedRhs :: [(CExpr,CExpr)] -> [CLocalDecl] -> CRhs

Data type for representing local (let/where) declarations

Constructors:

• CLocalFunc :: CFuncDecl -> CLocalDecl
• CLocalPat :: CPattern -> CRhs -> CLocalDecl
• CLocalVars :: [CVarIName] -> CLocalDecl

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)

Data type for representing pattern expressions.

Constructors:

• CPVar :: CVarIName -> CPattern
• CPLit :: CLiteral -> CPattern
• CPComb :: QName -> [CPattern] -> CPattern
• CPAs :: CVarIName -> CPattern -> CPattern
• CPFuncComb :: QName -> [CPattern] -> CPattern
• CPLazy :: CPattern -> CPattern
• CPRecord :: QName -> [CField CPattern] -> CPattern

Data type for representing Curry expressions.

Constructors:

• CVar :: CVarIName -> CExpr
• CLit :: CLiteral -> CExpr
• CSymbol :: QName -> CExpr
• CApply :: CExpr -> CExpr -> CExpr
• CLambda :: [CPattern] -> CExpr -> CExpr
• CLetDecl :: [CLocalDecl] -> CExpr -> CExpr
• CDoExpr :: [CStatement] -> CExpr
• CListComp :: CExpr -> [CStatement] -> CExpr
• CCase :: CCaseType -> CExpr -> [(CPattern,CRhs)] -> CExpr
• CTyped :: CExpr -> CQualTypeExpr -> CExpr
• CRecConstr :: QName -> [CField CExpr] -> CExpr
• CRecUpdate :: CExpr -> [CField CExpr] -> CExpr

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

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

Constructors:

• CSExpr :: CExpr -> CStatement
• CSPat :: CPattern -> CExpr -> CStatement
• CSLet :: [CLocalDecl] -> CStatement

Type of case expressions

Constructors:

• CRigid :: CCaseType
• CFlex :: CCaseType

Exported operations: