ocaml/ocaml

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The core OCaml system: compilers, runtime system, base libraries

Stars: 6.6k
Forks: 1.4k
Open beginner issues: 2
Indexed issues: 342
Avg merge: 3d 21h
Merged PRs (30d): 31

Dominant language: OCaml
License: No license data
Last GitHub push: Sep 17, 2026
Latest indexed: Sep 19, 2026
Contributing guide: Contributing guide
Code of conduct: Code of conduct
Beginner labels: good first issue

Beginner friendly Everything

Open All

342 open issues indexed

Clarify ambiguity in "Character literals" documentation regarding regular-char and UTF-8 Open

documentation-wish

Difficulty 1/5 Under an hour Newbie friendliness 90/100

ocaml/ocaml#15082 · Opened Sep 18, 2026
Runtime_events producer: missing bounds check on user event write Open

ocaml/ocaml#15074 · 2 comments · 1 assignee · Opened Sep 15, 2026
Runtime_events and exceptions from User event decoders Open

ocaml/ocaml#15072 · 3 comments · 1 assignee · Opened Sep 15, 2026
Fix `dup3`, `pipe2` detection with macOS 27 SDK leading to a crash Open

ocaml/ocaml#15067 · 1 comment · 1 assignee · Opened Sep 11, 2026
merge `flexdll` within the compiler repository Open

ocaml/ocaml#15058 · 1 assignee · Opened Sep 10, 2026
Re-exporting ADT gets rejected due to arity change Open

ocaml/ocaml#15053 · 2 comments · 1 assignee · Opened Sep 9, 2026
testsuite/tests/afl-instrumentation always fails if AFL is installed but OCaml is not configured with --with-afl Open

testsuite

ocaml/ocaml#15046 · 1 assignee · Opened Sep 7, 2026
Stop-the-world barriers take seconds on Windows when a domain repeatedly enters and leaves a blocking section Open

multicore Performance runtime-system

ocaml/ocaml#15042 · 8 comments · 1 assignee · Opened Sep 5, 2026
In-prefix tests fail in Windows CI Open

ocaml/ocaml#15040 · 1 assignee · Opened Sep 4, 2026
invalid unwind info in ocamlopt binaries in the stack reallocation path Open

ocaml/ocaml#15037 · 9 comments · 1 assignee · Opened Sep 2, 2026
Runtime events spam during full major collection Open

ocaml/ocaml#15024 · 2 comments · 1 assignee · Opened Aug 27, 2026
Tsan fails when configured with both --enable-flambda and --enable-tsan Open

ocaml/ocaml#15014 · 4 comments · 1 assignee · Opened Aug 20, 2026
Update "Polymorphism and its limitations" manual chapter for OCaml 5.5 Open

documentation

ocaml/ocaml#15013 · 1 comment · 1 assignee · Opened Aug 19, 2026
ocamldebug protocol clamps headers to 32 bits Open

ocaml/ocaml#15012 · 1 comment · 1 reaction · 1 assignee · Opened Aug 19, 2026
runtime_events: constructor indices are wire format and the header version does not track them Open

ocaml/ocaml#15011 · 5 comments · 2 assignees · Opened Aug 18, 2026
Atomic locs allow unsound writes to polymorphic record fields Open

ocaml/ocaml#14987 · 1 comment · 1 assignee · Opened Aug 5, 2026
int Atomic.t introduces polling points and calls to caml_atomic_fetch_add_field Open

ocaml/ocaml#14976 · 4 comments · 1 assignee · Opened Jul 31, 2026
Improve misleading typing error messages for Duplicate_constructor and Duplicate_label Open

Difficulty 2/5 1-3 hours Newbie friendliness 88/100

ocaml/ocaml#14958 · Opened Jul 25, 2026
Per domain timeouts Open

feature-wish

Difficulty 5/5 Over a week Newbie friendliness 35/100

ocaml/ocaml#14955 · 2 comments · Opened Jul 23, 2026
Handling of bigarray subarrays in Gc.Memprof Open

feature-wish

ocaml/ocaml#14938 · 2 comments · 1 assignee · Opened Jul 16, 2026
Scanf.unescaped fails on perfectly cromulent escaped strings ? Open

enhancement feature-wish stdlib

ocaml/ocaml#14930 · 3 comments · 1 assignee · Opened Jul 13, 2026
Functional updates of atomic records don't emit atomic loads Open

ocaml/ocaml#14918 · 7 comments · 1 reaction · 1 assignee · Opened Jul 7, 2026
GCC 14.4 broke C++ support with the Cygwin backend Open

ocaml/ocaml#14911 · 5 comments · 1 assignee · Opened Jul 7, 2026
The compiler seems to loop on file involving type identities and polymorphic variants Open

ocaml/ocaml#14905 · 4 comments · 1 assignee · Opened Jul 3, 2026
Equate two abstract types of a signature Open

feature-wish typing-modules

Difficulty 5/5 Over a week Newbie friendliness 35/100

ocaml/ocaml#14903 · 1 comment · Opened Jul 2, 2026
Add `Atomic.compare_and_exchange` Open

feature-wish stdlib

ocaml/ocaml#14889 · 1 comment · 1 reaction · 1 assignee · Opened Jun 26, 2026
OCaml 5.2 regression: Inlining of local closure variables Open

ocaml/ocaml#14876 · 20 comments · 1 assignee · Opened Jun 22, 2026
Gc.compact memory leak when vm.max_map_count is exceeded on 5.x Open

ocaml/ocaml#14865 · 5 comments · 1 assignee · Opened Jun 15, 2026
Object finalizers declared in `initializer` can prevent the object from being collected Open

ocaml/ocaml#14861 · 4 comments · 1 assignee · Opened Jun 14, 2026
`make world && make install` broken Open

ocaml/ocaml#14858 · 9 comments · 1 assignee · Opened Jun 12, 2026
`Fatal error: exception Ctype.Unify(_)` when buiding dolmen Open

ocaml/ocaml#14842 · 26 comments · 2 assignees · Opened Jun 2, 2026
OCaml 5.5: minor pretty-printing bug with Ptyp_functor (and extensions) Open

bug parsing

Difficulty 4/5 3-5 days Newbie friendliness 48/100

ocaml/ocaml#14809 · 2 comments · Opened May 14, 2026
`opam install --assume-built` fails: missing ocaml-variants-fixup.sh Open

ocaml/ocaml#14793 · 7 comments · 1 assignee · Opened May 6, 2026
`module type of M` accessed through a module alias strengthens functor parameter signatures, blocking application to siblings Open

ocaml/ocaml#14780 · 4 comments · 2 assignees · Opened Apr 30, 2026
[Win32] `Unix.select` raises "select.c: original file handle not found" Open

bug windows

Difficulty 4/5 3-5 days Newbie friendliness 68/100

ocaml/ocaml#14758 · 7 comments · Opened Apr 19, 2026
File `tools/cvt_emit.mll`, rules `command` and `string` are not exhaustive Open

ocaml/ocaml#14750 · 3 comments · 1 assignee · Opened Apr 16, 2026
Typechecker loops when checking inclusion of two isomorphic module types Open

bug recursive-modules

Difficulty 4/5 3-5 days Newbie friendliness 45/100

ocaml/ocaml#14743 · 1 comment · Opened Apr 14, 2026
Dynlink test fails intermittently on MSCV64 Open

flaky-ci-failure windows

ocaml/ocaml#14708 · 1 assignee · Opened Apr 3, 2026
Principal mode treats all types of things in modules as principal Open

typing

ocaml/ocaml#14686 · 2 comments · 1 reaction · 1 assignee · Opened Mar 26, 2026
Adding new extension points entries in the AST Open

devel-discussion feature-wish

Difficulty 5/5 Over a week Newbie friendliness 35/100

ocaml/ocaml#14668 · 21 comments · 1 reaction · Opened Mar 23, 2026
feature request: `OCAMLRUNPARAM=s=2MB` Open

feature-wish good first issue newcomer-job

ocaml/ocaml#14658 · 10 comments · 3 assignees · Opened Mar 18, 2026
Mutually-recursive functions and slowdowns in Coccinelle Open

Performance

ocaml/ocaml#14656 · 7 comments · 1 assignee · Opened Mar 18, 2026
Undesirable exponential typechecking time Open

feature-wish typing

ocaml/ocaml#14650 · 4 comments · 1 assignee · Opened Mar 16, 2026
what is a good default setting for the minor heap size? Open

feature-wish

Difficulty 5/5 Over a week Newbie friendliness 35/100

ocaml/ocaml#14634 · 7 comments · Opened Mar 9, 2026
[5.5] "The signature for this packaged module couldn't be inferred" in presence of recursive functions and first-class modules Open

ocaml/ocaml#14630 · 5 comments · 1 assignee · Opened Mar 7, 2026
Programmable Patterns for OCaml Open

feature-wish

Difficulty 5/5 Over a week Newbie friendliness 35/100

ocaml/ocaml#14627 · 6 comments · 2 reactions · Opened Mar 6, 2026
Tests that take too long on AppVeyor Open

CI

Difficulty 3/5 3-5 days Newbie friendliness 42/100

ocaml/ocaml#14621 · 1 comment · Opened Mar 6, 2026
Testsuite failures on Power+TSAN Open

ocaml/ocaml#14605 · 2 comments · 1 reaction · 1 assignee · Opened Feb 28, 2026
Segfaults and timeouts on parallel tests in cleanup-at-exit mode Open

bug

Difficulty 4/5 3-5 days Newbie friendliness 38/100

ocaml/ocaml#14594 · 31 comments · Opened Feb 26, 2026
GC pacing and default parameters in `5.5` Open

gc Performance

ocaml/ocaml#14533 · 9 comments · 1 assignee · Opened Feb 10, 2026

ocaml/ocaml

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