PAKCS: System Libraries

Here is the collection of libraries contained in the distribution of PAKCS. Most of these libraries have been implemented during the development of larger Curry applications. If you have suggestions for changes/improvements or if you want to contribute your own library, please contact Michael Hanus.

• Prelude: This is the standard prelude, i.e., the main library which is added to every Curry program.
• AllSolutions: This library contains a collection of functions for obtaining lists of solutions to constraints. These operations are useful to encapsulate non-deterministic operations between I/O actions in order to connects the worlds of logic and functional programming and to avoid non-determinism failures on the I/O level.
• Assertion: This library defines the datatype and functions for the Curry module tester "currytest".
• Char: This library contains some useful functions on characters.
• CLPFD: This library supports constraint programming with finite domain constraints.
• CLPR: This library supports constraint programming with arithmetic constraints over real numbers.
• CLPB: This library provides a Boolean constraint solver based on BDDs.
• Combinatorial: This library contains a collection of common non-deterministic and/or combinatorial operations.
• Constraint: This library contains some useful operations for constraint programming.
• CSV: This library supports reading/writing files in CSV (comma separated values) format that can be imported and exported by most spreadsheed and database applications.
• Database: Library for accessing and storing data in databases. The contents of a database is represented in this library as dynamic predicates that are defined by facts than can change over time and can be persistently stored. All functions in this library distinguishes between queries that access the database and transactions that manipulates data in the database. Transactions have a monadic structure. Both queries and transactions can be executed as I/O actions. However, arbitrary I/O actions cannot be embedded in transactions. The ideas of this library are described in this paper.
• DaVinci: This library supports the visualization of graphs by the daVinci graph drawing tool.
• Directory: This library supports the access to the directory structure of the underlying operating system.
• Distribution: This library contains functions to obtain information concerning the current distribution of the Curry implementation, e.g., compiler version, load paths, front end.
• Dynamic: This library supports the manipulation of dynamic predicates, i.e., predicates that are defined by facts than can change over time and can be persistently stored. The ideas of this library are described in this paper. Remark: This library has been revised to the library Database. Thus, it might not be further supported in the future.
• FileGoodies: A collection of useful operations when dealing with files.
• Float: A collection of operations on floating point numbers.
• Global: This library provides functionality for global entities. A global entity has a name declared in the program. Its value can be accessed and modified by IO actions. Furthermore, global entities can be persistent so that their values are stored across different program executions.
• GlobalVariable: This library implements global variables. A global variable has a name declared in the program. Its value can be accessed and modified by IO actions. Values of global variables can contain logic variables shared with computations running in the same computation space. As a consequence, values of global variables are not kept across different program executions.
• GUI: This library contains definitions and functions to implement graphical user interfaces for Curry programs. It is based on Tcl/Tk and its basic ideas are described in detail here. This library is an improved and updated version of the older library Tk. The latter might not be supported in the future.
• Integer: A collection of common operations on integer numbers.
• IO: This library contains IO operations, like reading and writing files, that are not already contained in the prelude.
• IOExts: This library contains some useful extensions to the IO monad, in particular, the implementation of a global state.
• JavaScript: A library to represent JavaScript programs.
• KeyDatabase: This library provides a general interface for databases (persistent predicates based on the library Database) where each entry consists of a key and an info part.
• KeyDatabaseSQLite: This library provides a general interface for databases (persistent predicates based on the library Database) where each entry consists of a key and an info part. It reimplements the interface of the module KeyDatabase based on the SQLite database engine.
• KeyDB: This library provides a general interface for databases (persistent predicates) where each entry consists of a key and an info part. Remark: This library has been revised to the library KeyDatabase. Thus, it might not be further supported in the future.
• List: This library contains some useful operations on lists which are not contained in the standard prelude.
• Maybe: This library contains some useful operations on the Maybe type which are not contained in the standard prelude.
• NamedSocket: This library contains operations for network programming with sockets where sockets are addressed by symbolic names rather than numbers.
• Parser: This library defines (functional logic) parser combinators to support a simple implementation of parsers in Curry. It is adapted from Rafael Caballero and Francisco J. Lopez-Fraguas: A Functional Logic Perspective of Parsing, Proc. FLOPS'99, Springer LNCS 1722, pp. 85-99, 1999
• Ports: This library supports the development of concurrent and distributed applications in Curry by defining ports for sending and receiving messages, possibly containing logical variables. A detailed description of the idea and use of ports can be found here.
• Pretty: This library provides combinators to support the definition of pretty printers for structured text.
• Profile: This library contains limited and preliminary support for profiling. Currently, it supports the possibility to show the time and space needed to evaluate a term to its normal form.
• PropertyFile: This library defines some functions to read and update files containing properties in the usual equational syntax.
• Read: This library defines some functions for reading special tokens (naturals, integers, hexadecimal numbers) from strings. This library is included for backward compatibility only. You should use the library ReadNumeric which provides a better interface for these functions.
• ReadNumeric: This library defines some functions for reading numeric tokens (naturals, integers, hexadecimal numbers) from strings and converting them to numbers.
• ReadShowTerm: This library contains functions for converting ground data terms to strings and vice versa.
• SetFunctions: This library contains a prototypical implementation of set functions to encapsulate nondeterministic computations. The general idea of set functions is described in this paper but the implementation in this library is more restricted than the general approach.
• Socket: This library contains basic operations for network programming with sockets.
• System: This library supports the access to parts of the system environment, like the current date and time, environment variables, system calls etc.
• Time: This library contains definitions and functions to handle date and time information.
• Tk: This library contains definitions and functions to implement graphical user interfaces for Curry programs. It is based on Tcl/Tk and described in detail here.
• Unsafe: This library contains unsafe operations which should not be used.

• Array: An implementation of arrays with Braun Trees.
• Dequeue: An implementation of double-ended queues supporting access at both ends in constant amortized time.
• FiniteMap: An implementation of finite maps. A finite map is an efficient purely functional data structure to store a mapping from keys to values.
• GraphInductive: A library for inductive graphs (port of a Haskell library by Martin Erwig). Graphs are composed and decomposed in an inductive way.
• Random: This library provides operations for generating pseudo-random number sequences.
• RedBlackTree: This library provides an efficient implementation of red-black trees. It serves as the base for the libraries SetRBT and TableRBT. All the operations on trees are generic, i.e., one has to provide explicit order predicates on elements.
• SetRBT: This library provides an efficient implementation of sets as red-black trees. The implementation is generic in the types of elements and the set operations require an ordering predicate on elements. The library also contains a generic sort function with complexity O(n*log(n)) based on insertion into red-black trees.
• Sort: A collection of useful functions for sorting and comparing characters, strings, and lists.
• TableRBT: This library provides an efficient implementation of tables (i.e., finite mappings from keys to values) as red-black trees. The implementation is generic in the types of keys and values and the table operations require an ordering predicate on keys.
• Traversal: This library supports lightweight generic traversals through tree-structured data.

• CategorizedHtmlList: This library provides functions to categorize a list of entities into a HTML page with an index access (e.g., "A-Z") to these entities.
• HTML: This library supports HTML and CGI programming, i.e., the generation of (dynamic) web pages. A detailed description of this library and its basic ideas can be found here.
• HtmlParser: This library contains a parser for HTML documents. It does not perform any syntax checks but returns only a generic representation according to the definition of HTML documents provided in the library HTML.
• Mail: This library contains functions for sending emails. The implementation might need to be adapted to the local environment.
• Markdown: Library to translate markdown documents into HTML or LaTeX.
• URL: This library contains functions related to URLs, in particular, downloading of documents accessible by a URL.
• WUI: Library to support type-oriented construction of web user interfaces. The ideas behind the application and implementation of this library are described in paper that is available via this web page.
• XML: Library for processing data in XML format. It contains a definition of a datatype for representing XML terms and a parser and pretty printing for converting strings into such XML terms and vice versa.
• XmlConv: This library provides type-based combinators to construct XML converters. Arbitrary XML data can be represented as algebraic datatypes and vice versa. See here for a description of this library.

• AbsCurry: This library contains a definition of an abstract representation of Curry programs in Curry. It is only included for backward compatibility and should not be used. Use the library AbstractCurry instead.
• AbsCurryIO: This library supports functions to read Curry program in the old AbsCurry representation (based on reading files in the new AbstractCurry format).
• AbstractCurry: This library contains a definition for representing Curry programs in Curry and an I/O action to read Curry programs and transform them into this abstract representation.
• AbstractCurryPrinter: This library contains a pretty printer for AbstractCurry programs in order to show an AbstractCurry program in standard Curry syntax.
• CompactFlatCurry: This library contains functions to reduce the size of FlatCurry programs by combining the main module and all imports into a single program that contains only the functions directly or indirectly called from a set of main functions.
• CurryStringClassifier: This library contains a simple tool to process strings containing Curry source code in order to perform simple manipulations of source programs (e.g., adding type signatures, removing comments).
• Flat: This library supports meta-programming, i.e., the manipulation of Curry programs in Curry. For this purpose, the library contains definitions of datatypes for the representation of so-called FlatCurry programs and an I/O action to read Curry programs and transform them into this representation.
  Remark: This library has been revised to the library FlatCurry. In the near future, it will not be further supported.
• FlatTools: This library extends the library Flat for meta-programming. It contains the definition of a show function for a string representation of FlatCurry programs, a function for showing FlatCurry expressions in (almost) Curry syntax, and an I/O action for storing a FlatCurry program into an .flc file (which can be further compiled by the Curry2Prolog compiler, compare the PAKCS User Manual).
  Remark: This library has been revised to the library FlatCurryTools. In the near future, it will not be further supported.
• FlatCurry: This library supports meta-programming, i.e., the manipulation of Curry programs in Curry. For this purpose, the library contains definitions of datatypes for the representation of so-called FlatCurry programs and an I/O action to read Curry programs and transform them into this representation.
  Remark: This library is a revised version of the library Flat, i.e., the representation of FlatCurry programs is improved to simplify the implementation of meta-programming tools (interpreter, compiler, analyzer etc.). In the near future, only this representation will be further supported.
• FlatCurryGoodies: This library provides selector functions, test and update operations as well as some useful auxiliary functions for manipulating FlatCurry data terms.
• FlatCurryRead: This library defines operations to read a FlatCurry programs or interfaces together with all its imported modules in the current load path.
• FlatCurryShow: This library contains functions to transform FlatCurry programs into string representations, either in a FlatCurry format or in a Curry-like syntax.
• FlatCurryTools: This library is outdated and might be deleted in future releases. Use the library FlatCurryShow instead of this library.
• FlatCurryXML: This library contains functions to convert FlatCurry programs into XML terms and vice versa.
• FlatXML: This library contains functions to convert FlatCurry programs into XML terms and vice versa. A detailed specification of the XML format used here can be found in http://www.informatik.uni-kiel.de/~curry/flat/.
• FlexRigid: This library provides a function to compute the rigid/flex status of a FlatCurry expression (right-hand side of a function definition).
• PrettyAbstract: This library contains a pretty printer for AbstractCurry programs in order to show an AbstractCurry program in human-readable Curry syntax. In contrast to the library AbstractCurryPrinter, this library implements a better human-readable pretty printing of AbstractCurry programs.