The op macro replaces syntax like @3 with gensyms. The problem is these genyms are not wrapped with (sys:var ...). For instance: `foo@{1}bar` ;; (sys:quasi "foo" (sys:var 1 () ()) "bar") might, inside an op expression turn into: (sys:quasi "foo" #:arg001 "bar") If this object is printed, it renders as `foo#:arg001bar` which is garbage syntax. After this fix, that will come out as: `foo@{#:arg001}bar` It is not read/print consistent, but it has the same meaning under evaluation. * lib.c (out_quasi_str_sym): New static function. Formed out of a block of code taken from out_quasi_str. (out_quasi_str): Print (sys:var ...) symbols via a call to out_quasi_str_sym, eliminating a block of code. If an element itself is a symbol, then print that using out_quasi_str_sym also.