{ [s]waps two variables. (varref; varref) → () }
[
  b:  { loads the value at the top of the stack into b }
  a:  { loads the value at the top of the stack into a }

  a;; t:  { loads the value stored in the variable stored in a (hence the double dereference) into t }
  b;; a;:  { loads the value stored in the variable stored in b into the variable stored in a }
  t; b;:  { loads the value stored in t into the variable stored in b }
]s:

{ [p]rints the three variables. }
[
  "X = " x;. 10,
  "Y = " y;. 10,
  "Z = " z;. 10,
]p:

77444 x:
12_ y:
0 z:

p;!

{ if x > y, swap x and y }
x;y;> [xys;!] ?

{ if y > z, swap y and z }
y;z;> [yzs;!] ?

{ if x > y, swap x and y }
x;y;> [xys;!] ?

"After sorting:
"

p;!