OCaml Online Compiler
Write, compile, and run OCaml code online directly from your browser with our free Online OCaml Compiler. Practice functional programming, pattern matching, recursion, modules, and strongly typed code without installing the OCaml toolchain, OPAM, or utop on your computer.
How to Use This OCaml Compiler
- Write or paste your OCaml code
Enter your program in the Code Editor. You can test functions, lists, tuples, pattern matching, recursion, records, variants, and other OCaml features supported by the execution environment. - Click the Run button
Select Run to execute your OCaml program. If your code contains a syntax, type, or runtime error, review the returned feedback, correct the relevant code, and run it again. - Check the Output screen
Your program result appears in the Output panel. Use the available controls to copy, download, or delete the output before testing another program.
Key Features
- Free Online OCaml Compiler: Write and execute OCaml programs directly from a modern web browser.
- Zero Installation: No need to install OCaml, OPAM,
utop, or configure a local development environment for supported programs. - Instant Execution: Click Run and quickly view your program output or compiler feedback.
- Standard OCaml Syntax: Practice functions, pattern matching, recursion, lists, tuples, records, variants, and other core language concepts.
- Strong Static Typing: Experiment with OCaml’s type inference and catch many type-related mistakes during compilation.
- Functional Programming Practice: Test immutable data, higher-order functions, recursive algorithms, and functional programming techniques.
- Dark and Light Mode: Switch the Code Editor theme for comfortable coding in different lighting conditions.
- Output Controls: Copy, download, or clear generated output directly from the Output panel.
1. How do I print output in this OCaml compiler using print_endline?
OCaml provides print_endline for printing a string followed by a newline.
Enter the code in the Code Editor, click Run, and view the result in the Output screen.
For formatted output, you can also use Printf.printf:
2. Do I need to install OCaml, OPAM, or utop to use this compiler?
No. You can use this Online OCaml Compiler directly from your browser without installing OCaml, OPAM, or utop locally for supported programs.
A local OCaml setup may still be preferable for larger projects, package management, external dependencies, debugging, or applications that require direct access to your operating system.
3. Does this compiler support standard OCaml modules and syntax?
The compiler is intended to support standard OCaml language features and commonly available modules in the configured runtime.
For example:
Common standard modules such as List, Array, String, and Printf may be available. Support for third-party OPAM packages or environment-specific libraries can vary.
4. Can I use pattern matching and recursion in this OCaml compiler?
Yes. Pattern matching and recursion are fundamental OCaml features and can be used to write concise functional programs.
This makes the compiler useful for learning OCaml’s functional style, type system, recursive functions, and pattern-matching techniques.