Introduced &IGN for ignored variables.

Used to be NIL, this is an incompatible change.  Rationale: otherwise
I would have to parse deconstructing lambda forms to distinguish from
other uses of NIL.

let-plus.lisp

@@ -6,7 +6,7 @@
 
 (defun ignored? (symbol)
   "Return a boolean determining if a variable is to be ignored."
-  (not symbol))
+  (eq symbol '&ign))
 
 (defun replace-ignored (tree)
   "Replace ignored variables in TREE with a gensym, return a list of these as

package.lisp

@@ -2,22 +2,22 @@
 
 (defpackage let-plus
   (:use cl alexandria anaphora)
-  (:export 
-   
+  (:export
+
    ;; basic user interface
-   
+
    let+
-
-   &accessors &accessors-r/o &slots &slots-r/o &structure &structure-r/o
+
+
+   #:&ign &accessors &accessors-r/o &slots &slots-r/o &structure &structure-r/o
    &values &array-elements &array-elements-r/o &flet &labels &macrolet
    &symbol-macrolet &plist &plist-r/o &hash-table &hash-table-r/o
 
    ;; defining new forms
-   
+
    let+-expansion let+-expansion-for-list define-let+-expansion
 
    ;; extensions
-
-   &flet+ &labels+ lambda+ defun+ define-structure-let+ &fwrap &assert 
-   &once-only &with-gensyms &complex))
 
+   &flet+ &labels+ lambda+ defun+ define-structure-let+ &fwrap &assert
+   &once-only &with-gensyms &complex))

tests.lisp

@@ -81,20 +81,20 @@ should)."
 
 (addtest (let-plus-tests)
   test-values
-  (let+ (((&values a nil c) (values 1 2 3)))
+  (let+ (((&values a &ign c) (values 1 2 3)))
     (ensure-same a 1)
     (ensure-same c 3)))
 
 (addtest (let-plus-tests)
   test-values-recursive
-  (let+ (((&values (a b) nil c) (values '(1 4) 2 3)))
+  (let+ (((&values (a b) &ign c) (values '(1 4) 2 3)))
     (ensure-same a 1)
     (ensure-same b 4)
     (ensure-same c 3)))
 
 (addtest (let-plus-tests)
   test-array
-  (let+ ((#2A((a nil) (b c)) #2A((1 2) (3 4))))
+  (let+ ((#2A((a &ign) (b c)) #2A((1 2) (3 4))))
     (ensure-same a 1)
     (ensure-same b 3)
     (ensure-same c 4))