I've been having fun with ranges lately. While nesting computing ranges I
noticed only the
outermost range's cache is necessary; there's no way of accessing front() of
ranges deeper
in the expression twice because they are sealed by the outermost range. Example:
map!"a._0 + a._1"( // caches, front() may be called twice
zip( // oh, trumpet: front() is called only to compute outer map's cache
map!"a*a"([2, 4, 5, 6]), // oh, trumpet
take(sequence!"a._0 + n * a._1"(1, 2), 4) // oh, trumpet
)
);
Eliminating superfluous caches, among other benefits, allows inlining the
(usually cheap)
front()s. One way to do it is to parametrize computing ranges with an enum
Cached.(yes|no).
What you think?
--
Tomek
