What is a CMI file? A CMI file is a compiled OCaml interface file. It contains data type and variable definitions used by an application developed in OCaml. CMI files are created by compiling OCaml .ML or MLI files.

More Information Objective Caml (OCaml) is an ML-based programming language that is used primarily to create symbolic computation applications and teach programming. To begin building (i.e. creating an executable file for) an application they developed using OCaml, a developer must first compile the application's ML and MLI files. When the developer compiles their ML or MLI file, OCaml produces a CMI file. The CMI file contains a compiled definition of the data types and variables included within the developer's application. Along with the CMO files created during the compilation process, the CMI file is used to continue constructing the application's executable file.