danefilipczak / petrushka

"my freedom will be so much the greater and more meaningful the more narrowly I limit my field of action and the more I surround myself with obstacles. Whatever diminishes constraint, diminishes strength. The more constraints one imposes, the more one frees one’s self of the chains that shackle the spirit." - Igor Stravinsky

Petrushka is a DSL for solving constraint problems in clojure.

It works by transpiling clojure data structures to minizinc, and aims to provide:

• expressive syntax that is idiomatic to clojure.
• type inference where possible
• helpful error messages

Solving requires that the minizinc compiler and solver are present in your path under the normal alias - minizinc.

(solve {:find {:a [:number] ;; declare a type
               :b [:set (range 10)]} ;; and an optional range
        :where [[:contains? :b :a]
                [:> :a 5]
                [:< :a 8]
                [:contains? #{7 8} :a]]})
=> {:a 7, :b #{0 1 2 3 4 5 6 7 8 9}}

;; solve without declaring types or ranges. Safe for integers, treats sets as empty sets when no range can be infered.
(solve-where [[:= :a 1] [:and [:> :b 2] [:< :b 4]]]) 
=> {:a 1 :b 3})

inspirations, similarities

clojure2minizinc

• A clojure interface to minizinc that provides more features and a syntax that closely resembles the corresponding minizinc code. For those already familiar with programming in minizinc, clojure2minizinc may offer more features.

Operations

op	returns	args
:<=	:boolean	:number:&:numbers
:when	:boolean	:boolean:boolean
:>	:boolean	:number:&:numbers
:if	:boolean	:boolean:boolean:boolean
:-	:number	:number:number:&:numbers
:or	:boolean	:boolean:&:booleans
:not	:boolean	:boolean
:true?	:boolean	:boolean
:>=	:boolean	:number:&:numbers
:iff	:boolean	:boolean:boolean:&:booleans
:xor	:boolean	:boolean:boolean:&:booleans
:+	:number	:number:number:&:numbers
:false?	:boolean	:boolean
:and	:boolean	:boolean:&:booleans
:contains?	:boolean	:set:number
:=	:boolean	:number:&:numbers
:<	:boolean	:number:&:numbers
:set=	:boolean	:set:set:&:sets