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Mercury (programming language)
Mercury is a functional logic programming language made for real-world uses. The first version was developed at the University of Melbourne, Computer Science department, by Fergus Henderson, Thomas Conway, and Zoltan Somogyi, under Somogyi's supervision, and released on April 8, 1995. Mercury is a purely declarative logic programming language. It is related to both Prolog and Haskell.[2] It features a strong, static, polymorphic type system, and a strong mode and determinism system. The official implementation, the Melbourne Mercury Compiler, is available for most Unix and Unix-like platforms, including Linux, macOS, and for Windows. OverviewMercury is based on the logic programming language Prolog. It has the same syntax and the same basic concepts such as the selective linear definite clause resolution (SLD) algorithm. It can be viewed as a pure subset of Prolog with strong types and modes. As such, it is often compared to its predecessor in features and run-time efficiency. The language is designed using software engineering principles. Unlike the original implementations of Prolog, it has a separate compilation phase, rather than being directly interpreted. This allows a much wider range of errors to be detected before running a program. It features a strict static type and mode system[2] and a module system. By using information obtained at compile time (such as type and mode), programs written in Mercury typically perform significantly faster than equivalent programs written in Prolog.[3][4] Its authors claim that Mercury is the fastest logic language in the world, by a wide margin.[2] Mercury is a purely declarative language, unlike Prolog, since it lacks extra-logical Prolog statements such as Notable programs written in Mercury include the Mercury compiler and the Prince XML formatter. The Software company ODASE has also been using Mercury to develop its Ontology-Centric software development platform, ODASE.[6] Back-endsMercury has several back-ends, which enable compiling Mercury code into several languages, including: Production level
Past
Mercury also features a foreign language interface, allowing code in other languages (depending on the chosen back-end) to be linked with Mercury code. The following foreign languages are possible:
Other languages can then be interfaced to by calling them from these languages. However, this means that foreign language code may need to be written several times for the different backends, otherwise portability between backends will be lost. The most commonly used back-end is the original low-level C back-end. Examples :- module hello.
:- interface.
:- import_module io.
:- pred main(io::di, io::uo) is det.
:- implementation.
main(!IO) :-
io.write_string("Hello, World!\n", !IO).
Calculating the 10th Fibonacci number (in the most obvious way):[7] :- module fib.
:- interface.
:- import_module io.
:- pred main(io::di, io::uo) is det.
:- implementation.
:- import_module int.
:- func fib(int) = int.
fib(N) = (if N =< 2 then 1 else fib(N - 1) + fib(N - 2)).
main(!IO) :-
io.write_string("fib(10) = ", !IO),
io.write_int(fib(10), !IO),
io.nl(!IO).
% Could instead use io.format("fib(10) = %d\n", [i(fib(10))], !IO).
main(IO0, IO) :-
io.write_string("fib(10) = ", IO0, IO1),
io.write_int(fib(10), IO1, IO2),
io.nl(IO2, IO).
Release scheduleThe stable release naming scheme was 0.1 up to 0.13 for the first thirteen stable releases. In February 2010 the Mercury project decided to name each stable release by using the year and month of the release. For example 10.04 is for a release made in April 2010. There is often also a periodic snapshot of the development system release of the day (ROTD) IDE and editor support
See also
References
External links |
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