Short Circuiting: How would I write if then else with short-circuiting?

Question

Is it possible to write a one-line if then else statement in a language that supports short-circuiting? It doesn't have to be language specific, just pseudocode.

In case you didn't know, short-circuiting means that a language will evaluate exp1 || exp2 || exp3 || exp4... (|| is the or operator) by first executing exp 1, then if it returns true, execute exp 2, and so on... However, the moment exp n returns false, it does not continue evaluating exp n+1 and anything after that.

Answer 1

Let's say you want to express:

if p then f() else g()

Using only || and &&, both short circuiting. You can do that like this:

(p && ( f() || 1 )) || g()

To test it, a quick script:

$ perl -E '$p=1; ($p && ( f() || 1 )) || g(); sub f { say "f() called" } sub g { say "g() called" }'
f() called
$ perl -E '$p=0; ($p && ( f() || 1 )) || g(); sub f { say "f() called" } sub g { say "g() called" }'
g() called
$