[erlang-questions] [eeps] EEP 9
Wed Mar 5 04:51:51 CET 2008
Taking a quick look at the erlang implementation, I noticed the
1) The strip_left and strip_right functions are internal, so it would
be better to put the when is_integer(Sc) clause up a level to check
it only once (and crash on the caller's function rather than an
internal one) and maybe add an is_binary clause for the target to be
2) strip_left and strip_right should be optimized to use skip indexes
into the binary rather than creating new binaries on each iteration:
<<_SkipLeft:SkipSize, Sc, _Rest/binary>> = Bin then recurse with
SkipSize + 1
3) The <<>> clause in strip_left is unnecessary, the pattern match
for the first character will fail and you can just return the whole
binary without knowing if it is empty. A similar fix is probably
needed for strip_right. You should see a speed improvement with long
prefix to strip on either end.
4) duplicate/2 should be a BIF, I would expect it to be used for very
large binary blocks and you wouldn't want the memory to thrash on
such a simple instruction.
5) If to_upper and to_lower is really wanted, a BIF will give a much
Take a look at my article on binary BIFs presented at the 2005 ICFP
conference for other ideas to improve performance of the library.
http://www.duomark.com/erlang/index.html has a link to both the
article in PDF and the code that obtained the performance numbers
quoted in the article.
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