[trishume]

I don't think monadic parser libraries have a real claim to be that difference. All the languages listed have excellent parsing libraries that make things similarly easy, if not by language power than by grammar DSL with embeddable code snippets.

I think if any library could make a real difference for Haskell it's most likely to be http://hackage.haskell.org/package/lens, which a Haskeller friend of mine claims could likely make a lot of the AST traversal and rewriting much terser.

[pwm]

While I found your article informative and interesting I think it only works in the very specific context of this assignment. Disallowing powerful language features/libraries means it's not a level playing field and thus not a fair comparison. Some languages standard libraries are tiny some are huge. Some languages have lots of advanced features. Eg. GP mentioned GADTs with which one can write type safe/correct by construction ASTs. In other words programs passing specific tests in a specific context does not imply they are comparable in terms of general correctness/robustness/maintainability (as you noted this re caught edge cases).

[howenterprisey]

Hoopl (data flow analysis) would also make a difference. I did a very similar project at my university in Haskell and Hoopl definitely saved us from writing quite a bit of code. We also used parser combinators in the frontend, which I think saved us time too.

[anaphor]

I've found PEGs (Parsing Expression Grammars) to make things extremely easy and terse. E.g. OMeta, Parsley, etc.

My experience with using both PEGs and parser combinators is that there isn't a huge difference in the total number of lines of code. On the other hand though, the syntax of PEGs would be easier to understand for someone who is familiar with BNF style notation.

[pyrale]

Recoding a viable subset of lens would have taken 50 locs in haskell. Likewise, rewriting parser combinators would not have taken long for experienced devs. The problem here is that requiring people to recode the libs on top of the compiler is disingenuous. And if you ban idiomatic libs, you also ban most online help, tutorials, etc.

[loup-vaillant]

(A suitable subset of) Parsec is about 100 lines of OCaml. Implementing a PEG syntax on top of it is about 150 lines of Haskell (or less, I'm a Haskell noob).

Building up the knowledge to get to this point however… nope, those students were better off going hand written recursive descent (or Lex/Yacc, since an equivalent was allowed).

https://github.com/LoupVaillant/Monokex/blob/master/src/pars...

http://loup-vaillant.fr/projects/metacompilers/nometa-haskel...