Welcome to HCODX Online Compiler
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Compile and run Brachylog code online instantly with HCODX. Our free cloud-based Brachylog compiler supports real-time execution, standard input, syntax highlighting, and code download. No installation or configuration required. Start coding in Brachylog now.
Run Brachylog instantly without installing any IDEs or configuring environments. Our cloud-based Brachylog handles libraries, runtimes, and dependencies automatically so you can focus on writing code.
Whether you are studying algorithms in Brachylog, practicing data structures in Brachylog, or exploring functional programming, our tool provides real-time stdout/stderr feedback with interactive standard input support.
HCODX is a free online compiler and code runner: write code in your browser, execute it on a cloud sandbox, and interact with your program through a live terminal. Students use it for coursework and interview practice; developers use it to test snippets in 85+ languages without setting up a local environment.
Declarative logic programming gets the golfing treatment in Brachylog, created by Code Golf Stack Exchange member Julien Cumin (known as Fatalize). The first version appeared in 2015 and the heavily redesigned v2 in 2017; both are built on top of SWI-Prolog. A Brachylog program is a chain of constraints relating an implicit input to an implicit output, so many challenges are solved by simply describing the answer and letting unification plus backtracking find it. That makes it a favorite for decision problems and combinatorics on Code Golf Stack Exchange. HCODX runs the full SWI-Prolog-backed interpreter in a genuine terminal session, so you can feed test cases through stdin interactively instead of configuring a Prolog stack yourself.
"Hello, World!"w
How it works: the string literal unifies the current value with "Hello, World!", then the predicate w writes that value to standard output. A Brachylog program is one chain of goals, so no boilerplate is needed.Brachylog shines on Code Golf Stack Exchange challenges that reduce to search or verification: primality, permutation properties, subset sums, and puzzle solving such as Sudoku-style constraints. Because backtracking is free, a few bytes can express what imperative golf languages need explicit loops for. It is also a compact way to introduce logic programming to students who find full Prolog syntax heavy, and a fun bridge for Prolog users into the esolang scene. HCODX is a free online Brachylog editor, runner and interpreter — an IDE-grade compiler and playground to write and run code online, execute code with live output and live preview, no downloads or web server required.
It helps but is not required. Brachylog inherits unification, nondeterminism, and backtracking from Prolog, so understanding those concepts makes programs click faster. The surface syntax is entirely different, though: single-character predicates chained left to right, with implicit input and output variables. Many golfers learn it directly from the GitHub wiki and existing Code Golf Stack Exchange answers.
On general challenges Jelly and 05AB1E usually win because of their larger built-in vocabularies and string compression. Brachylog pulls ahead when the task is naturally a constraint or decision problem, since stating a property is often shorter than computing it. A primality check or a find-the-permutation task can be dramatically terser in Brachylog.
By convention the program's implicit input variable is bound to the first command-line input, and the final output variable is printed if the predicate succeeds. Decision problems can simply succeed or fail, which interpreters report as true or false. Explicit writing is available through predicates like w, and stdin can supply values interactively in the HCODX terminal.
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