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------------------------------------------------------------------------------ --- This library supports meta-programming, 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 top-level and pattern matching is replaced by case expressions --- and disjunctions. --- --- @author Michael Hanus --- @version July 2016 ------------------------------------------------------------------------------ module FlatCurry.Types where --- 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. data Prog = Prog String [String] [TypeDecl] [FuncDecl] [OpDecl] deriving (Eq, Ord, Read, Show) --- 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 QName = (String, String) --- Data type to specify the visibility of various entities. data Visibility = Public -- public (exported) entity | Private -- private entity deriving (Eq, Ord, Read, Show) --- The data type for representing type variables. --- They are represented by `(TVar i)` where `i` is a type variable index. type TVarIndex = Int --- Kinded type variables are represented by a tuple of type variable --- index and kind. type 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. data TypeDecl = Type QName Visibility [TVarWithKind] [ConsDecl] | TypeSyn QName Visibility [TVarWithKind] TypeExpr | TypeNew QName Visibility [TVarWithKind] NewConsDecl deriving (Eq, Ord, Read, Show) --- A constructor declaration consists of the name and arity of the --- constructor and a list of the argument types of the constructor. data ConsDecl = Cons QName Int Visibility [TypeExpr] deriving (Eq, Ord, Read, Show) --- A constructor declaration for a newtype consists --- of the name of the constructor --- and the argument type of the constructor. data NewConsDecl = NewCons QName Visibility TypeExpr deriving (Eq, Ord, Read, Show) --- 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) data TypeExpr = TVar TVarIndex -- type variable | FuncType TypeExpr TypeExpr -- function type t1->t2 | TCons QName [TypeExpr] -- type constructor application -- TCons module name typeargs | ForallType [TVarWithKind] TypeExpr -- forall type deriving (Eq, Ord, Read, Show) data Kind = KStar | KArrow Kind Kind deriving (Eq, Ord, Read, Show) --- Data type for operator declarations. --- An operator declaration `fix p n` in Curry corresponds to the --- FlatCurry term `(Op n fix p)`. data OpDecl = Op QName Fixity Int deriving (Eq, Ord, Read, Show) --- Data types for the different choices for the fixity of an operator. data Fixity = InfixOp | InfixlOp | InfixrOp deriving (Eq, Ord, Read, Show) --- Data type for representing object variables. --- Object variables occurring in expressions are represented by `(Var i)` --- where `i` is a variable index. type VarIndex = Int --- Arity of a function. type 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. data FuncDecl = Func QName Arity Visibility TypeExpr Rule deriving (Eq, Ord, Read, Show) --- A rule is either a list of formal parameters together with an expression --- or an "External" tag. data Rule = Rule [VarIndex] Expr | External String deriving (Eq, Ord, Read, Show) --- Data type for classifying case expressions. --- Case expressions can be either flexible or rigid in Curry. data CaseType = Rigid | Flex -- type of a case expression deriving (Eq, Ord, Read, Show) --- Data type for classifying combinations --- (i.e., a function/constructor applied to some arguments). --- @cons FuncCall - a call to a function where all arguments are provided --- @cons ConsCall - a call with a constructor at the top, all arguments are provided --- @cons FuncPartCall - a partial call to a function (i.e., not all arguments --- are provided) where the parameter is the number of --- missing arguments --- @cons ConsPartCall - a partial call to a constructor (i.e., not all arguments --- are provided) where the parameter is the number of --- missing arguments data CombType = FuncCall | ConsCall | FuncPartCall Arity | ConsPartCall Arity deriving (Eq, Ord, Read, Show) --- Data type for representing expressions. --- --- Remarks: --- --- if-then-else expressions are represented as rigid case expressions: --- --- (if e1 then e2 else e3) --- --- is represented as --- --- (case e1 of { True -> e2; False -> e3}) --- --- Higher-order 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") []])) --- --- @cons Var - variable (represented by unique index) --- @cons Lit - literal (Int/Float/Char constant) --- @cons Comb - application `(f e1 ... en)` of function/constructor `f` --- with `n`<=arity(`f`) --- @cons Let - introduction of local variables via (recursive) let declarations --- @cons Free - introduction of free local variables --- @cons Or - disjunction of two expressions (used to translate rules --- with overlapping left-hand sides) --- @cons Case - case distinction (rigid or flex) --- @cons Typed - typed expression to represent an expression with a --- type declaration data Expr = Var VarIndex | Lit Literal | Comb CombType QName [Expr] | Let [(VarIndex, Expr)] Expr | Free [VarIndex] Expr | Or Expr Expr | Case CaseType Expr [BranchExpr] | Typed Expr TypeExpr deriving (Eq, Ord, Read, Show) --- 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). data BranchExpr = Branch Pattern Expr deriving (Eq, Ord, Read, Show) --- Data type for representing patterns in case expressions. data Pattern = Pattern QName [VarIndex] | LPattern Literal deriving (Eq, Ord, Read, Show) --- Data type for representing literals occurring in an expression --- or case branch. It is either an integer, a float, or a character constant. data Literal = Intc Int | Floatc Float | Charc Char deriving (Eq, Ord, Read, Show) ----------------------------------------------------------------------- --- 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. showQNameInModule :: String -> QName -> String showQNameInModule mod qn@(qmod, name) | qmod == mod || qmod == "Prelude" = name | otherwise = showQName qn --- Shows a qualified name. showQName :: QName -> String showQName (qmod, name) = qmod ++ '.' : name ----------------------------------------------------------------------- |