OCaml

OCaml was released in 1996 at INRIA, the French national computer science institute, by Xavier Leroy, Jérôme Vouillon, Damien Doligez, Didier Rémy, and others. It grew from the ML family of languages, first built in the 1970s to write proofs about programs. The trading firm Jane Street writes most of its software in it, and the Rocq proof assistant (formerly Coq) is written in it.

Like Haskell, OCaml is functional and checks every type before the program runs, working most of them out on its own. Unlike Haskell, it runs each line in order, and it lets you use loops and change arrays in place when that’s clearer. The standard library has lists, arrays, hash tables, sorting, and file reading. Packages from opam, OCaml’s package manager, aren’t installed here. The run script compiles each program to native code with ocamlopt and treats every warning as an error.

Quirks

• Integers and floats never mix, and floats have their own operators: +., -., *., and /.. 1 + 2.0 doesn’t compile; you convert with float_of_int.
• Integer / rounds toward zero, so -7 / 2 is −3, and -7 mod 3 is −1.
• = compares structure and == compares identity: [1; 2] = [1; 2] is true, while [|1|] == [|1|] is false.
• string_of_float 3. gives "3.", with no zero after the point. Printf.printf "%.6f" prints six decimals.
• A match that misses a case gets a warning, so here it doesn’t compile: function 0 -> "zero" | 1 -> "one" stops with “this pattern-matching is not exhaustive”.
• An unused variable is a warning too, so it also stops the build.
• Integers wrap around when they overflow: max_int + 1 = min_int is true.
• Reading past the end of an array raises Invalid_argument("index out of bounds") instead of reading memory.

git clone https://github.com/qnixon/dswithx.git
cd dswithx
python3 harness/run_tests.py --language ocaml