/* To exit the innermost block, use return(<value>) */

block([n],
   do (
      n: random(20),
      ldisp(n),
      if n = 10 then return(),
      n: random(20),
      ldisp(n)
   )
)$

/* To exit any level of block, use catch(...) and throw(<value>);
they are not used for catching exceptions, but for non-local
return. Use errcatch(...) for exceptions. */

block([n],
   catch(
      do (
         n: random(20),
         ldisp(n),
         if n = 10 then throw('done),
         n: random(20),
         ldisp(n)
      )
   )
)$

/* There is also break(<value>, ...) in Maxima. It makes Maxima
stop the evaluation and enter a read-eval loop where one can change
variable values, then return to the function after exit; For example */

block([x: 1], break(), ldisp(x));
> x: 2;
> exit;
2