> > The only feature I want is the ability to use a regex as a predicate.
> Would automatically forcing the first step to get a nice 'nil' be
>unacceptable?
Sounds good to me!
This can be quite easily accommodated:
(defn re-fn
"Construct a regular expression from string.
Calling a regular expression with no arguments returns a Pattern.
Calling a regular expression with a string argument
returns nil if no matches, otherwise the equivalent of (re-seq re
string)."
[string]
(let [pp (re-pattern string)]
(fn re
([] pp)
([s] (let [groups (re-seq pp s)]
(if (first groups)
groups
nil))))))
user=> ((re-fn "7.") "12324251")
nil
user=> ((re-fn "2.") "12324251")
("23" "24" "25")
user=> (if ((re-fn "1") "12") :great :bad)
:great
(And of course a wrapper implementation version could do something
similar).
Regards,
Tim.
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