OCaml in the context of Caml

A semantics encoding is a translation between formal languages. For programmers, the most familiar form of encoding is the compilation of a programming language into machine code or byte-code. Conversion between document formats are also forms of encoding. Compilation of TeX or LaTeX documents to PostScript are also commonly encountered encoding processes. Some high-level preprocessors, such as OCaml's Camlp4, also involve encoding of a programming language into another.

Formally, an encoding of a language A into language B is a mapping of all terms of A into B. If there is a satisfactory encoding of A into B, B is considered at least as powerful (or at least as expressive) as A.

In computer science, bootstrapping is the technique for producing a self-compiling compiler – that is, a compiler (or assembler) written in the source programming language that it intends to compile. An initial core version of the compiler (the bootstrap compiler) is generated in a different language (which could be assembly language); successive expanded versions of the compiler are developed using this minimal subset of the language. The problem of compiling a self-compiling compiler has been called the chicken-or-egg problem in compiler design, and bootstrapping is a solution to this problem.

Bootstrapping is a fairly common practice when creating a programming language. Many compilers for many programming languages are bootstrapped, including compilers for ALGOL, BASIC, C, Common Lisp, D, Eiffel, Elixir, Factor, Go, Haskell, Java, Modula-2, Nim, Oberon, OCaml, Pascal, PL/I, Python, Rust, Scala, Scheme, TypeScript, Vala, Zig and more.

Camlp4 is a software system for writing extensible parsers for programming languages. It provides a set of OCaml libraries that are used to define grammars as well as loadable syntax extensions of such grammars. Camlp4 stands for Caml Preprocessor and Pretty-Printer and one of its most important applications was the definition of domain-specific extensions of the syntax of OCaml.

Camlp4 was part of the official OCaml distribution which is developed at the INRIA. Its original author is Daniel de Rauglaudre. OCaml version 3.10.0, released in May 2007, introduced a significantly modified and backward-incompatible version of Camlp4. De Rauglaudre maintains a separate backward-compatible version, which has been renamed Camlp5. All of the examples below are for Camlp5 or the previous version of Camlp4 (versions 3.09 and prior).

Xavier Leroy (born 15 March 1968) is a French computer scientist and programmer. He is best known for his role as a primary developer of the OCaml system. He is Professor of software science at Collège de France. Before his appointment at Collège de France in 2018, he was senior scientist (directeur de recherche) at the French government research institution Inria.

Leroy was admitted to the École normale supérieure in Paris in 1987, where he studied mathematics and computer science. From 1989 to 1992 he did his PhD in computer science under the supervision of Gérard Huet.