Unusual behaviour of symbol-macrolet

core.clj

(ns timetable.core
  (:refer-clojure :exclude [==])
  (:use [clojure.core.logic]
        [clojure.tools.macro]))

;; Basic form. Works
(run 10 [q]
     (== [(lvar) (lvar) (lvar)] q)
     (membero :history q)
     (membero :math q)
     (membero :physics q))
;;([:history :math :physics] [:math :history :physics] [:history :physics :math] [:math :physics :history] [:physics :history :math] [:physics :math :history])

;; Using a macrolet, also works
(run 10 [q]
     (symbol-macrolet [_ (lvar)]
                      (== [_ _ _] q))
     (membero :history q)
     (membero :math q)
     (membero :physics q))
;;([:history :math :physics] [:math :history :physics] [:history :physics :math] [:math :physics :history] [:physics :history :math] [:physics :math :history])


;; Using a macrolet, does not work.  Only difference is scope of macrolet
(run 10 [q]
     (symbol-macrolet [_ (lvar)]
                      (== [_ _ _] q)
                      (membero :history q)
                      (membero :math q)
                      (membero :physics q)))
;; ((:physics . _.0) (_.0 :physics . _.1) (_.0 _.1 :physics . _.2) (_.0 _.1 _.2 :physics . _.3) (_.0 _.1 _.2 _.3 :physics . _.4) (_.0 _.1 _.2 _.3 _.4 :physics . _.5) (_.0 _.1 _.2 _.3 _.4 _.5 :physics . _.6) (_.0 _.1 _.2 _.3 _.4 _.5 _.6 :physics . _.7) (_.0 _.1 _.2 _.3 _.4 _.5 _.6 _.7 :physics . _.8) (_.0 _.1 _.2 _.3 _.4 _.5 _.6 _.7 _.8 :physics . _.9))

;;  Wrap entire thing with a macrolet.  This works.
(symbol-macrolet [_ (lvar)]
 (run 10 [q]
      (== [_ _ _] q)
      (membero :history q)
      (membero :math q)
      (membero :physics q)))

;;([:history :math :physics] [:math :history :physics] [:history :physics :math] [:math :physics :history] [:physics :history :math] [:physics :math :history])

project.clj

(defproject timetable "1.0.0-SNAPSHOT"
  :description "FIXME: write description"
  :dependencies [[org.clojure/clojure "1.3.0"]
                 [org.clojure/core.logic "0.6.7"]
                 [org.clojure/tools.macro "0.1.1"]])