non-Erlang Erlang grammars
Mon Oct 23 15:12:19 CEST 2000
Ulf Wiger <> writes:
>I've spent some time pondering the match specifications for trace
>and (not yet released) ets. While the functionality is powerful
>and much wanted, I think it's really too bad that one can't specify
>the filters using Erlang pattern matching syntax, which is already so
One thing I thought might be a good way to solve this this problem
would be to use funs, BUT be extremely restrictive in what is allowed
within the fun, basically matching and simple BIFs. No function calls
at all or data creation either.
This checking could be done at run time so no extra langauge constructs
or definitions are necessary.
What it can't do is allow you to construct match specifications on the
The problem with all this is of course that as an ets table doesn't
exist within any process there is no context in which to evaluate the
fun. Therefore you have to be extremely restrictive. With a bit of
trickery you could probably allow calls to local functions as long as
they obey the ame restricitive rules. To handle recursion just allow
at most one time slice per check, anything longer results in a fail, or
While this operationally might not give you more than match specs it at
least uses existing features in a relatively clean way. And I agree,
match specs are ugly.
Robert Virding Tel: +46 (0)8 545 55 017
Alteon Web Systems Email:
S:t Eriksgatan 44 WWW: http://www.bluetail.com/~rv
SE-112 34 Stockholm, SWEDEN
"Folk säger att jag inte bryr mig om någonting, men det skiter jag i".
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