Re: dash.el [was: Re: Imports / inclusion of s.el into Emacs]

[Joost Kremers]

On Tue, May 12 2020, Richard Stallman wrote:
>   > (map #(/ % 2) '(2 4 6 8))
>
>   > It's quite neat (the % being the equivalent of dash.el's 
>   > `it`).
>
> In Lisp we have always preferred to write things in the more 
> general
> form where you specify the arg names.  But a shorter construct
> which avoid the need to specify the arg names might be ok.

In Clojure, they're called function literals and the Clojure docs 
say "[...] idiomatic use would be for very short one-off 
mapping/filter fns and the like." So basically just what you said.

> What could that kind of abbreviated lambda-expression look like?

In Clojure, a function literal is written with `#(...)`, and it 
supports `%n` for arguments, where n=1,2,3... (Actually, I don't 
know if Clojure supports `%10` and up or if it just goes up to 
`%9`, but I guess that doesn't matter much). A single `%` is 
synonymous with `%1`, which is used when there's only one 
argument. Also supported is `%&`, which is similar to `&rest 
<var>` in Elisp, being bound to a list containing the remaining 
arguments.

That's all there is to it (the official doc is ever shorter: 
fourth bullet point under 
<https://clojure.org/reference/reader#_dispatch>).

--
Joost Kremers
Life has its moments