I like the lispiness and features of ITERATE but it breaks source location for debugging errors in SBCL with SLIME. Instead the ITER form is indicated, which dampens my enthusiasm for it somewhat.

  (defpackage :test
    (:use :cl :iterate))

  (in-package :test)

  (defun test-iter ()
    (declare (optimize (debug 3) (safety 3) (speed 0)))
    (iter:iter   ;;; <-- highlights whole ITER form
      (sleep 2)
      (error "test")))

  (defun test-loop ()
    (declare (optimize (debug 3) (safety 3) (speed 0)))
    (loop
      :do (sleep 2)
      :do (error "test")))   ;;; <-- highlights ERROR form

Iterate also breaks the count function. Or did the last time I tried to use it.

What do you mean?

Just checked and this is still a problem. Try this code with Iterate:

  (let ((list '(1 2 3 4 1 2 3 4))) ;; or whatever other sequence
    (iter (for i from 1 to 10)
          (sum (count i list))))

It will error out on you. The same works fine with loop:

  (let ((list '(1 2 3 4 1 2 3 4)))
    (loop for i from 1 to 10
          sum (count i list))) ;; => 8

Now, that's a bit contrived as an example, but an iteration library should not break a standard library function call.

https://gitlab.common-lisp.net/iterate/iterate/-/issues/12 - Apparently it's known and they intend to remove it in 2.0, which isn't out yet.

good to know, thanks