Module "FlatCurry.curry"

Library to support meta-programming in Curry.
This library contains a definition for representing FlatCurry programs in Curry (type "Prog") and an I/O action to read Curry programs and transform them into this representation (function "readFlatCurry").

Author: Michael Hanus

Version: August 2005

Exported names:

Summary of exported functions:

readFlatCurry :: String -> IO Prog

I/O action which parses a Curry program and returns the corresponding FlatCurry program.

readFlatCurryWithParseOptions :: String -> FrontendParams -> IO Prog

I/O action which reads a FlatCurry program from a file with respect to some parser options.

readFlatCurryFile :: String -> IO Prog

I/O action which reads a FlatCurry program from a file in ".fcy" format.

readFlatCurryInt :: String -> IO Prog

I/O action which returns the interface of a Curry program, i.e., a FlatCurry program containing only "Public" entities and function definitions without rules (i.e., external functions).

writeFCY :: String -> Prog -> IO ()

Writes a FlatCurry program into a file in ".fcy" format.

showQNameInModule :: String -> (String,String) -> String

Translates a given qualified type name into external name relative to a module.

Imported modules:

Directory
Distribution
Prelude
ReadShowTerm

Exported datatypes:

QName

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)

TVarIndex

The data type for representing type variables. They are represented by (TVar i) where i is a type variable index.

Type synonym: TVarIndex = Int

VarIndex

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

Prog

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 translation_table) where modname: name of this module, imports: list of modules names that are imported, typedecls, opdecls, functions, translation of type names and constructor/function names: see below

Constructors:

Prog:: String -> [String] -> [TypeDecl] -> [FuncDecl] -> [OpDecl] -> Prog

Visibility

Data type to specify the visibility of various entities.

Constructors:

Public:: Visibility
Private:: Visibility

TypeDecl

Data type for representing definitions of algebraic data types.
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:: (String,String) -> Visibility -> [Int] -> [ConsDecl] -> TypeDecl
TypeSyn:: (String,String) -> Visibility -> [Int] -> TypeExpr -> TypeDecl

ConsDecl

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

Constructors:

Cons:: (String,String) -> Int -> Visibility -> [TypeExpr] -> ConsDecl

TypeExpr

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", "Success", "()" (unit type), "(,...,)" (tuple types), "[]" (list type)

Constructors:

TVar:: Int -> TypeExpr
FuncType:: TypeExpr -> TypeExpr -> TypeExpr
TCons:: (String,String) -> [TypeExpr] -> TypeExpr

OpDecl

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

Constructors:

Op:: (String,String) -> Fixity -> Int -> OpDecl

Fixity

Data types for the different choices for the fixity of an operator.

Constructors:

InfixOp:: Fixity
InfixlOp:: Fixity
InfixrOp:: Fixity

FuncDecl

Data type for representing function declarations.
A function declaration in FlatCurry is a term of the form
(Func name arity type (Rule [i_1,...,i_arity] e))
and represents the function "name" with definition
name :: type
name x_1...x_arity = e
where each i_j is the index of the variable x_j.
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:: (String,String) -> Int -> Visibility -> TypeExpr -> Rule -> FuncDecl

Rule

A rule is either a list of formal parameters together with an expression or an "External" tag.

Constructors:

Rule:: [Int] -> Expr -> Rule
External:: String -> Rule

CaseType

Data type for classifying case expressions. Case expressions can be either flexible or rigid in Curry.

Constructors:

Rigid:: CaseType
Flex:: CaseType

CombType

Data type for classifying combinations (i.e., a function/constructor applied to some arguments).

Constructors:

FuncCall:: CombType: FuncCall - a call to a function where all arguments are provided
ConsCall:: CombType: ConsCall - a call with a constructor at the top, all arguments are provided
FuncPartCall:: Int -> CombType: FuncPartCall - a partial call to a function (i.e., not all arguments are provided) where the parameter is the number of missing arguments
ConsPartCall:: Int -> CombType: ConsPartCall - a partial call to a constructor (i.e., not all arguments are provided) where the parameter is the number of missing arguments

Expr

Data type for representing expressions.
Remarks:

if-then-else expressions are represented as function calls:
(if e1 then e2 else e3)
is represented as
(Comb FuncCall ("Prelude","if_then_else") [e1,e2,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 = success
is represented as
(Rule [0] (Comb FuncCall ("Prelude","cond") [Comb FuncCall ("Prelude","=:=") [Var 0, Lit (Intc 2)], Comb FuncCall ("Prelude","success") []]))

Constructors:

Var:: Int -> Expr: Var - variable (represented by unique index)
Lit:: Literal -> Expr: Lit - literal (Integer/Float/Char constant)
Comb:: CombType -> (String,String) -> [Expr] -> Expr: Comb - application (f e1 ... en) of function/constructor f with n<=arity(f)
Let:: [(Int,Expr)] -> Expr -> Expr
Free:: [Int] -> Expr -> Expr: Free - introduction of free local variables
Or:: Expr -> Expr -> Expr: Or - disjunction of two expressions (used to translate rules with overlapping left-hand sides)
Case:: CaseType -> Expr -> [BranchExpr] -> Expr: Case - case distinction (rigid or flex)

BranchExpr

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:

Branch:: Pattern -> Expr -> BranchExpr

Pattern

Data type for representing patterns in case expressions.

Constructors:

Pattern:: (String,String) -> [Int] -> Pattern
LPattern:: Literal -> Pattern

Literal

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

Exported functions:

readFlatCurry :: String -> IO Prog

I/O action which parses a Curry program and returns the corresponding FlatCurry program. Thus, the argument is the file name without suffix ".curry" (or ".lcurry") and the result is a FlatCurry term representing this program.

readFlatCurryWithParseOptions :: String -> FrontendParams -> IO Prog

I/O action which reads a FlatCurry program from a file with respect to some parser options. This I/O action is used by the standard action readFlatCurry. It is currently predefined only in Curry2Prolog.

Example call: (readFlatCurryWithParseOptions progfile options)

Parameters:
: progfile - the program file name (without suffix ".curry")
: options - parameters passed to the front end

readFlatCurryFile :: String -> IO Prog

I/O action which reads a FlatCurry program from a file in ".fcy" format. In contrast to readFlatCurry, this action does not parse a source program. Thus, the argument must be the name of an existing file (with suffix ".fcy") containing a FlatCurry program in ".fcy" format and the result is a FlatCurry term representing this program.

readFlatCurryInt :: String -> IO Prog

I/O action which returns the interface of a Curry program, i.e., a FlatCurry program containing only "Public" entities and function definitions without rules (i.e., external functions). The argument is the file name without suffix ".curry" (or ".lcurry") and the result is a FlatCurry term representing the interface of this program.

writeFCY :: String -> Prog -> IO ()

Writes a FlatCurry program into a file in ".fcy" format. The first argument must be the name of the target file (with suffix ".fcy").

showQNameInModule :: String -> (String,String) -> String

Translates a given qualified type name into external name relative to a module. Thus, names not defined in this module (except for names defined in the prelude) are prefixed with their module name.

Further infos:

incompletely defined

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