On 22 Okt., 23:24, André Thieme <[EMAIL PROTECTED]> wrote:
> This version of replace-placeholders still misses the numbered
> args %1, %2, .. as the reader would also steal those from me.
> In the end the #(..) macro would do it, instead of §.
So what I just did was extending it for this demostration by using
$1, $2, .. instead.
First we need two little helpers:
(defn digit-char? [char]
({\0 0 \1 1 \2 2 \3 3 \4 4 \5 5 \6 6 \7 7 \8 8 \9 9} char))
(defn numbered-arg? [arg]
(let [[$ & nums] (str arg)]
(and (= $ \$)
(every? digit-char? nums))))
Btw, something like digit-char? would be nice for the boot.clj
And now caring for the $n case:
(defn replace-placeholders2 [body]
((fn [args num-args new-body [f & r :as b]]
(if (not b)
[(seq args) (seq new-body)]
(cond (= f '_) (let [gensym (gensym)]
(recur (conj args gensym)
num-args
(conj new-body gensym)
r))
(numbered-arg? f) (if-let val (get num-args f)
(recur args num-args (conj new-body
val) r)
(let [gensym (gensym)]
(recur (conj args gensym)
(assoc num-args f gensym)
(conj new-body gensym)
r)))
:default (recur args num-args (conj new-body f) r))))
[] {} [] body))
As I see it this might even support nested currying if only the outer
one uses $1, $2, $3, ...
Example: #(map #(+ 3) %1 %1)
Translated §(map §(+ 3) $1 $1) and moved the § inside:
user> ((§ map (§ + 3) $1 $1) (range 1 10) (range 200 300) (range 5000
6000))
(5205 5209 5213 5217 5221 5225 5229 5233 5237)
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