There are these pages on the wiki regarding closures, and a reference to needing to change the internals of tcl_ObjType in order to implement them. https://wik

There are these pages on the wiki regarding closures, and a reference to needing to change the internals of tcl_ObjType in order to implement them. https://wiki.tcl-lang.org/page/Closures https://wiki.tcl-lang.org/page/Closures https://wiki.tcl-lang.org/page/Emulating+closures+in+Tcl https://wiki.tcl-lang.org/page/Emulating+closures+in+Tcl TCL 9 has surely fiddled with tcl_ObjType I hope, but it doesn't seem like it from a glance.