issue #4 -- recognize the mixed case

src/printers.lisp

@@ -45,13 +45,17 @@
     ((symbol name)
      (write-char #\' stream)
      ;; escape a backslash
-     (loop
-        for c across name
-        do
-          (if (char= #\\ c)
-              (progn (write-char #\\ stream)
-                     (write-char #\\ stream))
-              (write-char (char-downcase c) stream)))
+     (let ((mixed-case-p
+            (not (every (disjoin #'upper-case-p
+                                 (complement #'both-case-p))
+                        name))))
+       (loop
+          for c across name
+          do
+            (if (char= #\\ c)
+                (progn (write-char #\\ stream)
+                       (write-char #\\ stream))
+                (write-char (if mixed-case-p c (char-downcase c)) stream))))
      (write-char #\' stream))
     ((string*)
      (format stream "'~a'" term))

t/package.lisp

@@ -80,6 +80,14 @@
                                halt)
                            (:- (initialization main)))
                          *interpreter-class* :debug *debug*)))
+  (is (equal "Anakin-Skywalker"
+             (run-prolog `((parent-of luke-skywalker |Anakin-Skywalker|)
+                           (:- main
+                               (parent-of luke-skywalker ?who-is-it)
+                               (write ?who-is-it)
+                               halt)
+                           (:- (initialization main)))
+                         *interpreter-class* :debug *debug*)))
   (is (equal "\\=" ; string for \=
              (run-prolog `((parent-of luke-skywalker \\=) ; lisp symbol \= ; quoted prolog '\\=' ; prolog \=
                            (:- main