menhir¶

A menhir stanza is available to support the Menhir parser generator.

To use Menhir in a Dune project, the language version should be selected in the dune-project file. For example:

(using menhir 2.0)

This will enable support for Menhir stanzas in the current project. If the language version is absent, Dune will automatically add this line with the latest Menhir version once a Menhir stanza is used anywhere.

The basic form for defining menhir-git parsers (analogous to ocamlyacc) is:

(menhir
 (modules <parser1> <parser2> ...)
 <optional-fields>)

<optional-fields> are:

(merge_into <base_name>) is used to define modular parsers. This correspond to the --base command line option of menhir. With this option, a single parser named base_name is generated.
(flags <option1> <option2> ...) is used to pass extra flags to Menhir.
(infer <bool>) is used to enable Menhir with type inference. This option is enabled by default with Menhir language 2.0.

Menhir supports writing the grammar and automation to the .cmly file. Therefore, if this is flag is passed to Menhir, Dune will know to introduce a .cmly target for the module.

(explain <blang expression>) is used to control the generation of the .conflicts file explaining conflicts found while generating the parser. The condition is specified using the Boolean Language. This field was introduced in version 3.0 of the Menhir extension.

Note that starting in version 3.0 of the Menhir extension, the .conflicts file is generated by default. If this is not desired, it needs to be disabled explicitly by using the (explain) field.