[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...