On Friday, 29 November 2019 at 15:49:24 UTC, Paul Backus wrote:
It's actually a much simpler reason: filter calls .front twice
for each element in its input (once to check if the value
satisfies the predicate, and then again to return the value if
it does), and the range returned by map doesn't save the value
of .front between calls, so it has to re-compute it each time
by calling the transform function.
This makes it clear.
In my case a cache which can access all the previous elements
would be a too big thing, so I will do the filtering in a later
stage manually. But most importantly, now I know what's going on,
Thank You!
