[eeps] EEP 31

Fredrik Svahn <>
Thu Dec 10 22:29:41 CET 2009


Is there any chance of allowing part/[2,3] to be used as a guard? For tuples
there is already element/2. Something like the following would be very

my_func(Pos, Bin, Pattern) when binary:part(Bin, Pos, size(Pattern)) ==
Pattern ->

Another nice to have would be a diff function returning either the first
position where a list of binaries differ, or a tuple with the common
beginning and the differing ends of the binaries, e.g.

binary:diff([<<"abcde">>, <<"abcdghie">>]) -> 4, or
binary:diff([<<"abcde">>, <<"abcdghie">>]) -> {<<"abcd">>, <<"e">>,

The name diff might be somewhat misleading, maybe
longest_common_prefix/suffix is more descriptive (borrowed from Joe
Armstrongs elib_misc)?

BR /Fredrik

On Thu, Nov 26, 2009 at 3:25 PM, Patrik Nyblom <> wrote:

> A new EEP is submitted.
> EEP 31 is a slight rework of a part of EEP 9.
> Comments on this EEP are accepted until 10-Dec-2009. Please send all
> comments and suggestions to this mailing list ().
> Best regards,
> /The OTP team/Patrik
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