On Sat, Feb 5, 2011 at 10:14, B Smith-Mannschott <bsmith.o...@gmail.com> wrote:
> I considered that, but decided against it because vector is the
> conventional syntax for variable bindings in Clojure (let, fn,
> defrecord, ...) Once I'd decided to do that, it became clear that the
> first of the forms would become the initialization expression for the
> binding.
>
> On the other hand, reusing the vector syntax is not entirely fitting
> because it's limited to binding a single symbol without destructuring,
> so maybe it's not such a bad idea:
>
> (defmacro thread-with [varname & expressions]
> {:pre [(symbol? varname) (not (namespace varname))]}
> `(let [~@(interleave (repeat varname) (drop-last expressions))]
> ~(last expressions)))
>
> ;; e.g.
> ;; (thread-with x 2 (+ 1 x) (/ x 2))
> ;; => 3/2
>
> Having now broken the notational convention that always puts variable
> bindings in a vector once, we might as well break it again by
> borrowing let1 from common lisp:
>
> (defmacro let1 [bindable-form init-expression & body]
> `(let [~bindable-form ~init-expression]
> ~@body))
>
> ;; e.g.
> ;; (let1 x 1 (inc x))
> ;; => 2
> ;; but also supports destructuring
> ;; (let1 [x y] [1 2] [y x])
> ;; => [2 1]
> ;; potentially confusing to read?
I've published these two macros and a few other bits as
adiutores-parva on github.
https://github.com/bpsm/adiutores-parva/blob/master/src/main/clojure/bpsmithmannschott/adiutores/parva.clj
// Ben
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