Camlp4 Deprecation Warning: this tutorial describes technology that is considered obsolete. It’s been replaced by extensions points and ppx rewriters. Camlp4 is part of the standard OCaml distribution and Camlp5 is distributed The title of the tutorial says Camlp4 but that is because it was written prior to the. Many of the tutorials below need updating and tutorials on many new topics are Camlp4 Tutorial (by Jake Donham), to build syntax extensions for OCaml with.

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CamlP4 is the version included in the official OCaml distribution, maintained by the core team; CamlP4 is mostly compatible with the old CamlP4, but enough changes were made so that most code written for the old version does not work with the current one. Conceptually, the plan is simple: Some things CamlP4 can do, like integration of external syntaxes in OCaml programs, are not easy to replicate in Lisp.

Daniel de Rauglaudre wrote the original CamlP4, which was available for OCaml since its early versions. The following example defines a syntax extension of OCaml. The section about the Revised syntax in the latest official reference manual for the old CamlP4 version 3. So as an example: Several libraries are provided which facilitate the specific manipulation of OCaml syntax trees.

For now, there are no better options, so the only way out is to read both sources and try to integrate them mentally.


Camlp4 – Wikipedia

This tree can also be filtered before printing. Putting it all together: Tutoriial Documents The semi-official documentation: It is or was completely compatible with the old versions of CamlP4, although apparently it is now introducing incompatible changes.

By using this site, you agree to the Terms of Use and Privacy Policy. Camlp4 is a software system for writing extensible parsers for programming languages. The reason for the title will be explained in a bit. Between parsing and printing, it is possible to define AST Filters that can transform the tree, including maps and folds over it. Instead, each template has gaps that must be filled with data which depends on the situation.

The ocaml beta announcement: The sequence could yutorial better. The supplied tutoriak as of this pages’ creation is very small.

OCaml Tutorials – OCaml

So CamlP4 parses its input and then builds an abstract syntax tree out of it. Jake Donham probably knows a lot more about this stuff than me, but sometimes he seems to be writing to people who already know about CamlP4, especially in the first few posts.

Quotations allow the programmer to treat a piece of code as data instead of being part of the program itself.

Although the definition of grammars must be done in OCaml, the parser that is being defined or extended is not necessarily related to OCaml, in which case the syntax tree that is being manipulated is not the one of OCaml.


Retrieved from ” https: Most of them are linked in a previous part.

CamlP4 has a printer that emits the AST in a binary, marshaled form for the OCaml compiler, which can then skip the parsing stages and use the tree directly. He also uses quotations in original syntax in the earlier parts, rendering the example code unusable in current versions of OCaml in some cases he linked to newer versions that work. It is not necessary to use a.

Other target languages can also be campp4, such as C. CamlP4 makes it easy to create parsers, because it includes an embedded notation for parser generation. It is also possible to have a quotation inside an antiquotation, and an antiquotation inside this quotation that is inside the antiquotation of the original quotation, and so on.

A (meta-)guide to CamlP4: Metaprogramming in OCaml

It can be output in a binary form, e. From the point of view of syntax extensions for OCaml, CamlP4 parses OCaml code, most likely using an extended syntax, generates an AST that may be filtered, and then prints it.

Jake Donham has written a series of posts in his blog about CamlP4.