Fuzion • Tutorial • Conditional Expression

Conditional Expression

Internally if/else desugars to a match expression. See syntax sugar for more information.

The if expression provides a simple control flow mechanism to chose between two branches. Its use is straightforward:

print_count(count i32, item String) unit
pre
  count >= 0
=>
{
  if (count = 0)
  {
    yak("no")
  }
  else
  {
    yak(count)
  }
  yak(" $item")
  if (count != 1)
  {
    yak("s")
  }
  say("")
}

print_count(3, "apple")
print_count(1, "pear")
print_count(0, "apple")
print_count(2, "pear")

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print_count(count i32, item String) unit
pre
  count >= 0
=>
{
  if (count = 0)
  {
    yak("no")
  }
  else
  {
    yak(count)
  }
  yak(" $item")
  if (count != 1)
  {
    yak("s")
  }
  say("")
}
print_count(3, "apple")
print_count(1, "pear")
print_count(0, "apple")
print_count(2, "pear")
 
 
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What are effects?

A conditional expression can form the else clause of a previous conditional expression:

print_count(count i32, item String) unit
pre
  count >= 0
=>
{
  (cnt, plural) :=
    if      (count = 0) { ("no"  , $"s") }
    else if (count = 1) { ("one" , "" ) }
    else                 { ($count, $"s") }
  say("$cnt $item$plural")
}

print_count(3, "apple")
print_count(1, "pear")
print_count(0, "apple")
print_count(2, "pear")

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print_count(count i32, item String) unit
pre
  count >= 0
=>
{
  (cnt, plural) :=
    if      (count = 0) { ("no"  , $"s") }
    else if (count = 1) { ("one" , "" ) }
    else                 { ($count, $"s") }
  say("$cnt $item$plural")
}
print_count(3, "apple")
print_count(1, "pear")
print_count(0, "apple")
print_count(2, "pear")
 
 
הההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההה
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What are effects?

Singeline If Expressions

Keyword then is often required in single-line if-expressions:

x := if (true || false && true) then { "yes"; } else { "no"; };

say(x);

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x := if (true || false && true) then { "yes"; } else { "no"; };
say(x);
 
 
הההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההה
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What are effects?

last changed: 2024-06-28

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