Clojurians Log v2

hi everyone, i’m using core.logic to help me implement http://mason.gmu.edu/~rhanson/equatalk.html

my problem is that i want the additional constraint that the numbers should form a roughly normal distribution

not sure if that gist link above is coming through right, but core.logic part starts at line 46

is there a way to do that with core.logic?

actually, let me ask another simpler question first: what’s a good way to sort a list of numbers in core.logic, or to find the median of them?

you would have to express it as relations

each element in list X is one of the elements in list Y

the first element in list X is less than the second, etc

I am sure it can be done, but I am not sure I would do it

the logic stuff is sort of a combination of generators that generate possible matches and filters that reject things that don't match

so you'll end up generating all permutations of Y and rejecting the ones where your sorted relation doesn't hold

when you say you’re not sure you would do it, is it because of performance reasons?

it just seems like a mismatch between sorting and relational programming

maybe there is a paper some way with some cool prolog quicksort or something

me saying it seems like a mismatch, this guy saying it is beautiful

https://www.cp.eng.chula.ac.th/~piak/teaching/dsys/2004/quick-prolog.htm

aha: https://github.com/clojure/core.logic/blob/master/src/main/clojure/clojure/core/logic/bench.clj#L395-L396

can’t say i understand how it works or even how to use it yet

do you, @hiredman ?

e.g. why does qsorto there have [l r r0] ?

I believe the [l r r0] line is for tabling

tabling is some kind of optimization sort of like memoizing

okay, cool

so if i’m looking for a constraint that says that the list is sorted

which is not say I understand qsorto

and i have the qsorto as written there…

i clearly have more reading to do 🙂