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OCaml Ecosystem Extensions List

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Yunxing Dai edited this page Jun 14, 2016 · 9 revisions

OCaml/Reason Extension List

The OCaml community frequently uses file extension to distinguish between types of source, artifacts, metadata, etc. This README documents them and is intended to be newcomer-friendly. Feel free to contribute!

Prior Knowledge

Some terms come back often in the following explanations. (TODO: better explanation for all these. Feel free to modify this page directly!)

  • Bytecode: interpreter mode.
  • Native: runs on bare metal assembly instructions of the platform in question.
  • Linking: the step where the compiler takes many intermediate built result files and assemble them together. E.g. linking A with B, because A's original source file referred to B.
  • AST: Abstract Syntax Tree. The data structure coming from the source code, that the compiler operates on.
  • Object file: TODO.

The List

Every single one of these needs better explanations.

Official

Ext Description
ml OCaml source file.
mli OCaml interface (aka signature) file, that specifies nothing but the types of some (or all) of the corresponding ml file's values. Usually, during compilation, if foo.ml is provided but foo.mli isn't found, the latter will be automatically generated from the former.
cmo bytecode object (compiled module object-code)
cmi The result file compiled from the interface file (mli).
cma "Library" file. It's an archive that contains the bytecode compilation result (cmos). Handy for sharing.
cmxa like cma, but from native compilation. Holds cmo/o files.
cmxas cmxa, but for native dynamic linking using the Dynlink module.
cmx Contains extra info for linking and cross-modules optimizations.
out Somewhat conventional name/extension for the final output, produced by ocamlc/ocamlopt (e.g. ocamlc -o myExecutable.out), no special meaning (like C).
cmt Typed source file output (AST), generated from the compiler's -bin-annot (binary annotation) flag. Tools like Merlin and [ocp-index] (https://github.com/OCamlPro/ocp-index) use these files for code analysis.
cmti cmt, but for interface files.
annot Deprecated. See cmt.
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a
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Ecosystem

Ext Description
re Reason source file. The equivalent of ml for Reason.
rei Reason interface file. The equivalent of mli for Reason.
mliv Batteries-specific files for some custom preprocessing.
mllib Ocaml library (cma and cmxa).
mlpack Ocaml package (cmo built with the -pack flag).
odocl OCaml documentation.
mldylib Ocaml plugin (cma and cmxs).
mltop OCamlbuild top-level file, used by OCamlbuild to generate a .top file.
atd Atgen files, one of the libraries that helps generate Yojson boilerplate code. Here's an example.
mlpp Extlib-specific files for some custom preprocessing.
cmj BuckleScript intermediate files.
mly Merhir/ocamlyacc's grammar files.

References

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