Menhir is here!

Fukuoka.rb #333 Ninja Talk 大会『Menhir is here!』のスライド
https://fukuokarb.connpass.com/event/302318/

Transcript

1. Menhir is here! @ydah Fukuoka.rb #333 Ninja Talks 2023.11.29 (Wed.)
2. ɾ Name: Yudai Takada ɾ GitHub: @ydah / X: @ydah_ ɾ Software Engineer at ANDPAD, Inc. ɾ Member of RuboCop RSpec team ɾ Contributor of Lrama ɾ Implementation of Parameterizing rules ɾ Optimization of Lexer, etc. self.inspect
3. The world is about witness a Great Era of Parser!
4. But…
5. Don't touch the GC, the parser and the code generator. — Matz #rubyworld2023
6. That’s not true!
8. You should try!
9. Today's talk
10. Menhir is here!
11. • Highly functional LR(1) parser generator for the OCaml • OCaml also has a parser generator called ocamlyacc, Menhir is 90% compatible with ocamlyacc • Designed and implemented by François Pottier and Yann Régis-Gianas What is Menhir?
12. • Single, upright megalithic monument • The word menhir was adopted by 19th century archaeologists via the French • There is also famous menhir in Japan. There are many in Gifu By the Way
13. Why talking about OCaml's parser?
14. 6 MONTHS EARLIER…
16. https://bugs.ruby-lang.org/issues/19637
17. • LALR (1) parser generator written in Ruby • Created as a CRuby parser generator to replace GNU Bison. • The author is Yuichiro Kaneko • Ref: https://yui-knk.hatenablog.com/entry/2023/03/13/101951 • Ref: https://youtu.be/IhfDsLx784g?si=I3DG-ccG2rxbqxHd What is Lrama?
18. • Before replacing it with Lrama, Ruby had to support multiple Bison • It is not easy to maintain for multiple version • New features are added, but they are not available One of reasons replaced Bison
19. • Can break away from multiple versions of maintenance! • It will can use new features in Bison! (If we implement it) • Parser generator features other than Bison may be used! (if we implement it) The world after replacing Lrama
20. • Can break away from multiple versions of maintenance! • It will can use new features in Bison! (If we implement it) • Parser generator features other than Bison may be used! (if we implement it) The world after replacing Lrama
21. • We have the goal of making parse.y more readable • We need richer DSL for Lrama grammar fi les Provide rich syntax extensions
22. https://docs.google.com/presentation/d/ 1E4v9WPHBLjtvkN7QqulHPGJzKkwIweVfcaMsIQ984_Q
23. So
24. Menhir is here!
25. • Parameterizing rules • Rules can be parameterized with any number of symbols, called formal parameters • The standard library • A library of standard parameterization de fi nitions • Inlining • The %inline keyword helps avoid or resolve con fl icts without arti fi cially changing the grammar Useful Menhir Features
26. Useful Menhir Features • Parameterizing rules • Rules can be parameterized with any number of symbols, called formal parameters • The standard library • A library of standard parameterization de fi nitions • Inlining • The %inline keyword helps avoid or resolve con fl icts without arti fi cially changing the grammar
27. Parameterizing rules
28. • The de fi nition of a non-terminal symbol can be parameterized with other (terminal or non-terminal) symbols • Provide syntax sugar for common pattern for grammar rules Parameterizing rules
29. Parameterizing rules function_name(arg1, arg2) args : arg | args ',' arg ;
30. Parameterizing rules function_name(arg1, arg2) args : arg | args ',' arg ;
31. Parameterizing rules function_name(arg) args : arg | args ',' arg ;
32. Parameterizing rules function_name(arg1, arg2) args : arg | args ',' arg ;
33. Parameterizing rules function_name(arg) args : arg | args ',' arg ;
34. Parameterizing rules function_name(arg1, arg2) args : arg | args ',' arg ;
35. Parameterizing rules function_name(arg1, arg2, …) args : arg | args ',' arg ;
36. Parameterizing rules args : arg | args ',' arg ;
37. Parameterizing rules args : arg | args ',' arg ; args : separated_list(',', arg) ;
38. Parameterizing rules Name Recognizes Alias option(X) є | X X? list(X) a possibly empty sequence of X’s X* nonempty_list(X) a nonempty sequence of X’s X+ separated_list(sep, X) a possibly empty sequence of X’s separated with sep’s separated_nonempty_list(sep, X) a nonempty sequence of X’s   separated with sep’s
39. Tag for Parameterizing rules
40. Tag for Parameterizing rules %union { int i; char *str; } % t oken <i> NUMBER % t oken <str> S T RING
41. Tag for Parameterizing rules program: option(foo) program: option_foo option_foo: ε option_foo: foo
42. program: option(foo) { $$ = $ 1 } program: option_foo { $$ = $ 1 } option_foo: ε option_foo: foo Tag for Parameterizing rules
43. %union { int i; } program : option(foo) <i> ; Tag for Parameterizing rules
44. • Support for users to de fi ne rules • Support for nesting of parameterizing rules. e.g. `option(list(arg))` • Support for %inline Future Vision of Parameterizing rules
45. end