I agree with Perry. I've found I have to write two versions of
combine-preds often
(defn every-pred?
"Mimics AND"
[& preds]
(fn [& args] (every? #(apply % args) preds)))
(defn any-pred?
"Mimics OR"
[& preds]
(fn [& args] (some #(apply % args) preds)))
They're very handy, though. Makes it easy to create a complex
predicate from simple ones.
Sean
On Jan 21, 3:40 pm, Perry Trolard <trol...@gmail.com> wrote:
> I think it's easier to think about combining predicates separately
> from your file-filtering code. I'd use a higher-order function like
> the following
>
> (defn combine-preds
> [& preds]
> (fn [& args] (every? #(apply % args) preds)))
>
> then filter files like
>
> (filter (combine-preds pred1 pred2) (file-seq in-dir))
>
> Perry
>
> On Jan 21, 2:08 pm, nwalex <neillalexan...@gmail.com> wrote:
>
> > Brilliant. Thanks Dan, that did the trick.
>
> > On Jan 21, 8:01 pm, Dan Schmidt <dan.schm...@gmail.com> wrote:
>
> > > I don't know how efficient it is (or how idiomatic it really is), but
> > > this should work:
>
> > > (defn find-files
> > > "Find files in directory that match predicates pred & others"
> > > [in-dir pred & others]
> > > (reduce (fn [xs f] (filter f xs)) (file-seq in-dir) (cons pred others)))
>
> > > Dan
>
> > > On Thu, Jan 21, 2010 at 2:47 PM, nwalex <neillalexan...@gmail.com> wrote:
> > > > I'm very new to Clojure, and to functional programming in general. Can
> > > > anyone tell me the idiomatic way to implement this function?
>
> > > > (defn find-files
> > > > "Find files in directory that match predicates pred & others"
> > > > [in-dir pred & others]
> > > > (filter pred (file-seq in-dir)))
>
> > > > What is the best way to filter a sequence using multiple predicates? I
> > > > want to return a sequence containing the files that match predicate
> > > > pred and all other predicates bound to 'others'.
>
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