If and else

An if statement runs a block only when its condition is true:

if health <= 0 {
  status = "DEFEATED";
}

The condition follows if. The braces contain the branch controlled by that condition.

Choose between two branches

Add else for the false case:

if score >= goal {
  result = "WIN";
} else {
  result = "TRY_AGAIN";
}

Exactly one branch runs. The program continues after the complete statement.

Here is the same decision inside a complete Boop module:

var score: number = 0 with {
  input: true,
  min: 0,
};

text {
  let result = "Try again";

  if score >= 10 {
    result = "You win";
  }

  "{result}, @1!"
}

Add more branches

Use else if when the decision has several ordered cases:

if health <= 0 {
  status = "DEFEATED";
} else if health < 25 {
  status = "CRITICAL";
} else {
  status = "READY";
}

Sugar checks the conditions from top to bottom and runs the first matching branch.

Produce a value with if

When the decision itself should be an expression, use then and else:

let label = if score >= 10 then "Winner" else "Challenger";

This is a value-form if expression. Both branches produce a value, and that value is stored in label.

The same form can be used directly with Sugar text formatting:

text "@1 lands {}." with if critical then "a critical hit" else "a normal hit";

Use brace branches when code must run statements. Use if condition then value else value when one expression needs to choose a value.

The next lesson introduces functions: named operations that accept information and may produce a result.