undo some refactors

Author: fstamour

src/rewrites.lisp

@@ -44,9 +44,9 @@ Example patterns:
                 (assert (symbolp (car tree)) () "Functions must be constants in current impl")
                 `(application ,(car tree) ,@(mapcar #'compile-tree (cdr tree))))
                (t ; equivalent to (atom tree)
-                (and (symbolp tree)
-                     (string= "_" tree)
-                     (warn "Tried to compile a pattern involving a symbol named \"_\" in a package other than CLUCK. This will not be treated as a wildcard!"))
+                (when (and (symbolp tree)
+                           (string= "_" tree))
+                  (warn "Tried to compile a pattern involving a symbol named \"_\" in a package other than CLUCK. This will not be treated as a wildcard!"))
                 `(constant ,tree)))))
     (make-instance 'naive-pattern :compiled-tree (compile-tree pattern)
                                   :num-vars (length return-vars))))
@@ -117,13 +117,15 @@ Example patterns:
                              :test car=-fn))))))
 
 (defun default-car-match-fn (a b)
-  (unless (eql a b)
-    'no-match))
+  (if (eql a b)
+      nil
+      'no-match))
 
 (defun default-merge-car-bound-values-fn (a b id)
   (declare (ignore id))
-  (when (eql a b)
-    (values a t)))
+  (if (eql a b)
+    (values a t)
+    nil))
 
 (defclass graph-pattern (pattern)
   ((binding-restrictions

src/utils.lisp

@@ -9,8 +9,9 @@
 (defun hash-table-peek (ht)
   (with-hash-table-iterator (next ht)
     (multiple-value-bind (has-value-p k) (next)
-      (when has-value-p
-        (values k t)))))
+      (if has-value-p
+        (values k t)
+        (values nil nil)))))
 
 (declftype (hash-table) t hash-table-pop)
 (defun hash-table-pop (ht)

tests/pattern-matching.lisp

@@ -196,8 +196,9 @@
            "Allows bindings of the form (:exact sym) or (:bind sym). The former requires EQL between sym and the actual car and returns no bindings. The latter binds the car to the given symbol and never fails to match."
            (ecase (car binding-car)
              (:exact
-              (unless (eql (second binding-car) actual-car)
-                'no-match))
+              (if (eql (second binding-car) actual-car)
+                  nil
+                  'no-match))
              (:bind
               `((,(second binding-car) . ,actual-car))))))
     (with-e-graph eg