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 It’s been replaced by extensions points and ppx rewriters.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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Putting it all together: Actually, although the old CamlP4 had an official reference manual and tutorial, the new CamlP4 has neither. However, this type is recursive as expected for an AST and trees for any non-trivial piece of code will be complicated to create as a tuttorial of the AST type.

This post is meant to be a guide to the available documentation and tutorials about CamlP4, assuming no previous experience with it. Jake Donham has written a series of posts in his blog about CamlP4.

CamlP4 itself is written in this syntax. From Wikipedia, the free encyclopedia.

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

Furthering the difficulties, it is now fragmented CamlP4 and CamlP5 and not very well documented. It is not necessary to use a. Besides that, there are always the sources. The intention is to give the Big Picture, so that the tuforial can be worked out later. To learn CamlP4, you must learn this alt syntax. The good thing about grammars and parsers in CamlP4 is that they are extensible.


OCaml Tutorials – OCaml

Since OCaml is a multi-paradigm language, tutoril an interactive toplevel and a native code compiler, it can be used as a backend famlp4 any kind of original language. So as an example: CamlP4 uses an alternative concrete syntax for OCaml. 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.

The following example defines a syntax extension of OCaml. Expanders can also generate strings instead of AST nodes, although this is less useful. Daniel de Rauglaudre wrote the original CamlP4, which was available for OCaml since its early versions.

However, this has some disadvanges:. However, this has some disadvanges: For example, this piece of code: Camlp4the OCaml “pre-processor pretty printer” is an advanced macro system which allows complex abstract syntax tree transformations on ocaml programs, and on other recursive decent grammars.


To learn how to use quotations to generate OCaml AST nodes, you can look at this appendix from the same manual.

Before attempting to learn CamlP4, it is recommended to learn how to program in OCaml reasonably well, and to have at least some familiarity with parsing and programming language tools. As I mentioned, this is not a tutorial on CamlP4.

The supplied documentation as of this pages’ creation is very small. The user defines a grammar using a special notation, and CamlP4 generates a parser for it. Although the tutoriaal 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.

This brings up another source of confusion: In the beta announcement, there was mention of new binaries camlp4xxx that come preloaded with selections of new and old syntaxes. Filters and Printers So CamlP4 parses its input and then builds an abstract syntax tree out of it. And now for the punchline: Retrieved from ” https:

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