I have put up a bug at the sbcl bug tracker. The SUMMING macro didn't work due to a package lock violation when producing a FLET on the symbol SUM, which is also defined with a DEFUN in serapeum in generalized-array.lisp. This looks unintended to me so I am treating it as an sbcl bug. If they do not fix it then SUM can be pulled out to another unlocked package and imported into the serapeum package.
I have put up a bug at the sbcl bug tracker. The SUMMING macro didn't work due to a package lock violation when producing a FLET on the symbol SUM, which is also defined with a DEFUN in serapeum in generalized-array.lisp. This looks unintended to me so I am treating it as an sbcl bug. If they do not fix it then SUM can be pulled out to another unlocked package and imported into the serapeum package.
See https://bugs.launchpad.net/sbcl/+bug/1908803