4 ms·

There's also parser combinators, which (for example) are used in GHC's parser.

by thewakalix 5y ago

cosmic_quanta 5y ago
I find using parser combinators a joy. Makes parsing e.g. LateX somewhat straightforward
- aix1 5y ago
  I've not come across parser combinators. Is there good introductory material?
  - DylanSp 5y ago
    It's Haskell-based, but here you go: http://dev.stephendiehl.com/fun/002_parsers.html http://dev.stephendiehl.com/fun/002_parsers.html
eatonphil 5y ago
When I lookup "ghc parser" I get this page [0] that says the GHC parser is built from Happy [1], a Yacc-like parser generator. Grammar is here [2]. Could you link me to where you see GHC's parser using parser combinators? [0] https://gitlab.haskell.org/ghc/ghc/-/wikis/commentary/compiler/parser https://gitlab.haskell.org/ghc/ghc/-/wikis/commentary/compil... [1] https://www.haskell.org/happy/ https://www.haskell.org/happy/ [2] https://gitlab.haskell.org/ghc/ghc/-/blob/master/compiler/GHC/Parser.y https://gitlab.haskell.org/ghc/ghc/-/blob/master/compiler/GH...
- thewakalix 5y ago
  I was scanning the GHC source by eye, and misunderstood a comment about the "parsing monad". (Alex, the equivalent of lex, uses monads to describe actions, but I thought that monads were the main interface to the lexer.) Thanks for the correction.
valenterry 5y ago
Agreed! I would say that parser combinators are the sweet spot and the right choice in most cases. Scala has them as well, e.g.: https://com-lihaoyi.github.io/fastparse/ https://com-lihaoyi.github.io/fastparse/ And the good thing is, you don't have to learn a completely new language/syntax, you can use the host language's syntax and you have full IDE support as well.
CornCobs 5y ago
Agreed. I personally think of parser generator/parser combinator as similar to framework/library, where in the framework you have much less control and often have to rely on "escape hatches" to make custom stuff work. Whereas parser combinators are simply a library making implementing your parser much more convenient and expressive. You call the code, not the framework

There's also parser combinators, which (for example) are used in GHC's parser.

cosmic_quanta 5y ago

I find using parser combinators a joy. Makes parsing e.g. LateX somewhat straightforward

aix1 5y ago
I've not come across parser combinators. Is there good introductory material?
- DylanSp 5y ago
  It's Haskell-based, but here you go: http://dev.stephendiehl.com/fun/002_parsers.html http://dev.stephendiehl.com/fun/002_parsers.html

eatonphil 5y ago

When I lookup "ghc parser" I get this page [0] that says the GHC parser is built from Happy [1], a Yacc-like parser generator. Grammar is here [2]. Could you link me to where you see GHC's parser using parser combinators? [0] https://gitlab.haskell.org/ghc/ghc/-/wikis/commentary/compiler/parser https://gitlab.haskell.org/ghc/ghc/-/wikis/commentary/compil... [1] https://www.haskell.org/happy/ https://www.haskell.org/happy/ [2] https://gitlab.haskell.org/ghc/ghc/-/blob/master/compiler/GHC/Parser.y https://gitlab.haskell.org/ghc/ghc/-/blob/master/compiler/GH...

thewakalix 5y ago
I was scanning the GHC source by eye, and misunderstood a comment about the "parsing monad". (Alex, the equivalent of lex, uses monads to describe actions, but I thought that monads were the main interface to the lexer.) Thanks for the correction.

valenterry 5y ago

Agreed! I would say that parser combinators are the sweet spot and the right choice in most cases. Scala has them as well, e.g.: https://com-lihaoyi.github.io/fastparse/ https://com-lihaoyi.github.io/fastparse/ And the good thing is, you don't have to learn a completely new language/syntax, you can use the host language's syntax and you have full IDE support as well.

CornCobs 5y ago

Agreed. I personally think of parser generator/parser combinator as similar to framework/library, where in the framework you have much less control and often have to rely on "escape hatches" to make custom stuff work. Whereas parser combinators are simply a library making implementing your parser much more convenient and expressive. You call the code, not the framework