(btw I threw this together just before bed, so it's not perfect. One
thing that's wrong is it assumes (name x) can be called on any x; but
it can't be called on lots of things, like numbers. So you'd need to
filter those out, and also fix a couple other bugs.
On Dec 1, 2:12 am, Alan Malloy <a...@malloys.org> wrote:
> LoL lets you write:
>
> (with-cxrs
> (blah (foo (bar (cadddar x)))))
>
> ie, it looks in your source, sees what you need defined, and makes a
> letfn.
>
> This looked fun, so I banged out an implementation:
>
> (defn cxr-impl [name]
> (when-let [op (second (re-matches #"c([ad]+)r" name))]
> `(comp ~@(map {\a `first \d `rest} op))))
>
> (defmacro with-cxrs [& body]
> (let [symbols (remove coll? (tree-seq coll? seq body))]
> `(let [~@(for [sym symbols
> :let [impl (cxr-impl (name sym))]
> :when impl
> thing [sym impl]]
> thing)]
> ~@body)))
>
> user> (macroexpand-1 '(with-cxrs (inc (caadaaddadr x))))
> (let [caadaaddadr (comp first first rest first first rest rest first
> rest)]
> (inc (caadaaddadr x)))
>
> On Nov 30, 11:27 pm, Tassilo Horn <tass...@member.fsf.org> wrote:
>
>
>
>
>
>
>
> > Peter Danenberg <pe...@factual.com> writes:
>
> > Hi Peter,
>
> > > Try as I might, I can't purge these anachronisms; so here are `car' to
> > > `cddddr' in all their glory:
>
> > > http://clojars.org/cadr
>
> > Nice. :-)
>
> > > This implementation uses a Kleene-closure around the alphabet {a, d}
> > > to generate the names; and a macro to define them:
>
> > > https://github.com/klutometis/cadr/blob/master/src/cadr/core.clj
>
> > Is that inspired by the `cxr' macro (I think, that was its name) in Let
> > Over Lambda? One nice feature that seems missing from your version is a
> > macro for defining local functions on demand. I don't remember the
> > exact LoL syntax, but probably it would look something like that:
>
> > (with-cxrs [foo caaaddddddaddr,
> > bar caddddddddaaaaaaaar]
> > (cons (foo myseq) (bar mysec)))
>
> > Bye,
> > Tassilo
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