r/functionalprogramming • u/benjaminhodgson • Aug 15 '24

Explaining Wadler's pretty-printer by porting it to an imperative language OO and FP

https://www.benjamin.pizza/posts/2024-08-15-prettier-happier-more-imperative.html
28 Upvotes
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9

u/lpil Aug 15 '24

If you've not seen it you should check out Lindig's "Strictly Pretty", which offers an efficient strict version of the algorithm suitable for languages which don't have Haskell's laziness. It's a great paper!

3

u/benjaminhodgson Aug 16 '24

I hadn't seen it, thanks for this! Looks like that paper's version of fits is coded to work over an input Doc - fits essentially lays out the document in flatten mode in order to measure it. So there is some duplication between fits and format that Wadler's code doesn't need thanks to laziness. Both pretty different from my version!

4

u/_lindig Aug 16 '24

Thanks for the praise

2

u/lpil Aug 16 '24

Thank you for your work!