core.logic questions

gistfile1.clj

  (def form '(defmacro nom [x] (some (delicious)) forms))
  
  ;;this works nicely
  (let [x    (lvar)
        rest (lvar)]
    (run* [q]  
          (== form (llist 'defmacro x rest))
          (== q x)))
  ;;=> (nom)
  
  ;;why not this?
  (let [x    (lvar)
        rest (lvar)]
    (run* [q]  
          (== form `(defmacro ~x . ~rest))
          (== q x)))
  ;;=> ()

  ;;This doesn't work either
  (run* [q]
        (prep '(all
                (== form (defmacro ?x . ?rest))
                (== q ?x))))
  ;;=> java.lang.ClassCastException: clojure.lang.PersistentList cannot be cast to clojure.lang.IFn
  
  
  ;;This also works
  (run* [q]
        (fresh [pat alt]
               (membero [pat alt]
                        [(prep '[(defmacro ?x . ?rest)
                                 ?x])])
               (== pat form)
               (== q alt)))
  ;;=> (nom) 

  ;;why not this?
  (run* [q]
        (fresh [pat alt]
               (membero [pat alt]
                        [(prep '[#(== % (defmacro ?x . ?rest))
                                 #(== % ?x)])])
               (pat form)
               (alt q)))
  ;;=> clojure.core.logic.LVar cannot be cast to clojure.lang.IFn

The . symbol doesn't mean anything special - that would require Clojure reader support. Macros like defne and tools like the simple unifier handle the . symbol themselves.

Thanks @swannodette, that is good to know.
I'm still missing something though; e.g., I have no idea why the last form doesn't work.

logic vars aren't functions, they just store values. You need to project the vars first if you want to do that.