Problem Statement

List the conditional structures offered by a programming language. See Wikipedia: conditionals for descriptions. Common conditional structures include if-then-else and switch. Less common are arithmetic if, ternary operator and Hash-based conditionals. Arithmetic if allows tight control over computed gotos, which optimizers have a hard time to figure out.

Let's start with the solution:

t : " true"  ,t
f : " false" ,t
true  if t
false ifnot f
true  ifelse t f

onetwo : drop " Neither one nor two" ,t    # default declared first
onetwo : dup 2 = then " Two" ,t
onetwo : dup 1 = then " One" ,t

dup 0 = || ,t    # avoid printing a null string