Clojurians Log v2

@nihilazo has joined the channel

hi, I'm having some trouble with core.logic and function arities. I'm going through the reasoned schemer to learn and I've been trying to write some of my own relations as exercises. I wrote a simple implementation of concat which worked fine, and I tried to convert it to a relation:

(defn dumb-concat [x y]
  (cond
    (empty? y) x
    (empty? x) y
    :else (recur (conj x (first y)) (rest y))))

(defn dumb-concato [x y out]
  (l/conde
    [(l/emptyo y) (l/== out x)]
    [(l/emptyo x) (l/== out y)]
    [l/succeed (l/fresh [f r c]
                   (l/conso f r y)
                   (l/conjo x f c)
                   (dumb-concato c r)
                   )]))

however, when I try and test this with (l/run 1 [q] (dumb-concato [0 1 2 3] [5 4 3] q)) it just says Wrong number of args (2) passed to: logic-practice.core/dumb-concato

what am I doing wrong? Or is this a bug?

because I'm certainly passing 3 arguments to it (the two vectors and the lvar)

@jimmy has joined the channel

(dumb-concato c r)

^ That line looks like the error to me.

Dum-concato is just a regular function, not a core.logic relation, so you can't use it like that

Err

Dumb-concat

What exactly a core.logic relation is kind of complicated, but a recursive definition would be something like, a core.logic relation is a function whose body is composed of core.logic relations

So dumb-concato would be a relation if it didn't call dumb-concat, but the body of dumb-concat is all non-relations (it is all functions from clojure.core)

The kind of problem you get with calling clojure.core functions in a logic program is they don't know how to deal with logic variables

And relations don't return values, but functions do

Oh

I misread your code though

What I read as a call to dumb-concat is actually a call to dumb-concato with the wrong number if arguments which is exactly what the error you got says

...how did I miss the obvious mistake

thanks guys

somehow managed to make that mistake almost every time