Oops, while should be: TO WHILE :COND :BLOCK IF RUNRESULT :COND [RUN :BLOCK WHILE :COND :BLOCK] END But this does fail when you do some things i

Oops, while should be: TO WHILE :COND :BLOCK IF RUNRESULT :COND [RUN :BLOCK WHILE :COND :BLOCK] END But this does fail when you do some things in the block, like [OUTPUT] (equivalent of return). Also looking closer at UCBLogo macros and they are evaluated at runtime in a way I didn't expect. That is, they are expanded at call time, and can self-reference causing repeated expansions (but the expansions are immediately evaluated so the program size isn't effected). But I think they really could have accomplished the same thing more easily with the Tcl uplevel command.