Re: Scheme books [was: lat? and atom? not in guile?]

[Matt Wette <matt.wette@gmail.com>]

On 06/21/2018 06:44 AM, Joshua Branson wrote:
> Matt Wette <matt.wette@gmail.com> writes:
>
> And on this topic, I'm currently reading 'The Reasoned Schemer,' written
> in the same style.   The style gets the stuff into my head w/o resorting to
> trying out problems on the computer (yet).
> Hmmm. I've heard about the seasoned schemer, but not the reasoned one.
> I also have downloaded Structure and Interpretation of Computer
> Programs.  I need to actually spend some time going through it.
>
> I've just got several programming projects that I want to do, and I need
> to remind myself that I probably can't learn it all at once.  :)

The Reasoned Schemer is about miniKanren, a Scheme library thatuses
unification to generate a system of relations (versusfunctions).For
example, while (append '(a b) '(c d)) => '(a b c d), miniKanren can
solve "find x such that (append '(a b) x) yields '(a b c d)" :

   scheme@(guile-user)> (run* (x) (appendo '(a b) x '(a b c d)))
   $2 = ((c d))

where appendo is defined as:
(define appendo
   (lambda (l s ls)
     (conde
       ((== '() l) (== s ls))
       ((fresh (a d res)
      (== `(,a . ,d) l)
      (== `(,a . ,res) ls)
      (appendo d s res))))))

check https://dl.acm.org/citation.cfm?id=3110252

Matt