A Programming Language Learner's Resource. Contains descriptions of many ineresting programming languages, like APL, ABC, FP, Factor with examples and further links.
I can actually define this in TCL:
% proc ifn't {cond cmds} {if {!$cond} {uplevel $cmds}} % ifn't false {puts 12} 12 % ifn't true {puts 12} %
I can actually define this in TCL: