fukamachi / assoc-utils Goto Github PK

CL-USER> (defparameter *a* '((:a . 1) (:b . 2)))
*A*
CL-USER> (assoc-utils:delete-from-alist *a* :a)
((:B . 2))
CL-USER> *a*
((:A . 1) (:B . 2))
CL-USER> (assoc-utils:delete-from-alistf *a* :a)
((:B . 2))
CL-USER> *a*
((:B . 2))
CL-USER> 

In Mac, SBCL 1.4.6

It is common practice to have multiple entries in an alist with the same key. E.g. CLtL2 explicitly touts this as a feature:

Moreover, because the searching function assoc searches the a-list in order, new entries can ``shadow'' old entries

The order of keys should thus be maintained in alist=, otherwise this function might e.g. return non-nil for '(("foo" . 1) ("foo" . 2)) and '(("foo" . 2) ("foo" . 1)).

(loop 
   for i in *long-list*
   with sum = nil
   do (if (assoc-utils:aget sum i)
          (incf (assoc-utils:aget sum i))
          (push (cons i 0)  sum))
   finally (return sum))

Would be nicer to be able to write

(loop 
   for i in *long-list*
   with sum = nil
   do (incf (assoc-utils:aget sum i 0))
   finally (return sum))