On Mon, 4 May 2020, at 11:36, Ludovic Courtès wrote: > > One thing I found is that `match` is slow. The code looked nicer but had to > > change it back to lets and conds as the performance > > increase was ~2 seconds. > > Oh, in which case exactly? And are you sure your hand-written code is > equivalent to the ‘match’ code (it’s common for hand-written code to be > more lax than ‘match’)? > > One thing to pay attention to is the use of ‘list?’, which is O(N), and > is implied by ellipses in ‘match’. If you want to use ‘match’ in a way > that avoids ‘list?’, write patterns such as (a . b) instead of (a b ...). > It doesn’t have the same meaning, but often the end result is the same, > for instance because you’ll later match on ‘b’ anyway. > > (I wish we can one day have a proper list type disjoint from pairs…)
The change is here: he is only matching against chars and predicates: https://github.com/aconchillo/guile-json/commit/ad4b06d86e4822466983d00f55474c8f664b538d
