OCamlRV

OCamlRV is an interpreter for a small subset of OCaml. It includes a parser, an error-reporting Hindley-Milner type inferencer, and an evaluator with support for recursive values and functions.

The project is implemented in OCaml and uses Dune as its build system.

Features

• Integer, boolean, string, unit, list, option, and tuple values
• Arithmetic, comparison, equality, boolean, and unary operators
• if expressions and match expressions
• Anonymous functions, function application, and partial application
• Pattern matching with variables, constants, lists, cons cells, tuples, and type annotations
• Non-recursive and recursive let bindings, including mutually recursive bindings
• Let-polymorphism and static type inference
• Parse-tree output and interpreter debug output

Requirements

• OCaml
• Dune
• The dependencies listed in OCamlRV.opam

For an opam-based setup, install the project dependencies with:

opam install . --deps-only

Building

Build the project with Dune:

dune build

The executable is available as bin/main.exe after building.

Usage

The runner reads a source file passed as its positional argument. At least one operation flag should be supplied:

dune exec -- main path/to/program.ml -interpret

Available flags:

Flag	Description
-interpret	Evaluate the program and print its output
-inference	Infer the types in the program and report type errors
-dparsetree	Print the parsed representation of the program
-debug	Enable interpreter debug output

Several flags can be combined. For example, to inspect the parse tree and then interpret the example program:

dune exec -- main bin/example.ml -dparsetree -interpret

The runner can also read a program from standard input when no input filename is given:

printf 'let x = 2 + 3\n' | dune exec -- main -inference

Example program:

let rec factorial n =
	if n <= 1 then 1 else n * factorial (n - 1)

let () = print_int (factorial 5)

Testing and development

Run the Dune test suite, including cram tests:

dune runtest

The Makefile provides common development targets:

make          # Build the project
make fmt      # Format and promote formatting changes
make lint     # Run Dune lint checks
make zanuda   # Run checks, tests, and Zanuda

The zanuda target uses Zanuda.

Property-based tests can be run through the QuickCheck executable:

dune exec -- quickcheck

Project structure

• lib/ast.ml - abstract syntax tree definitions
• lib/parser.ml - source parser
• lib/inferencer.ml - type inference
• lib/interpreter.ml - evaluator
• bin/main.ml - command-line runner
• manytests.t/ - typed and ill-typed example programs
• tests/ - unit and property-based test support

License

OCamlRV is distributed under the LGPL-3.0-or-later license. See COPYING.LESSER for the license text.

Copyright 2024-2025 Viacheslav Sidorov and Danila Rudnev-Stepanyan.