Branches

Branches take a boolean expression, then will only execute a single block of code depending on the condition. You can chain multiple conditions with the elif clause. With an optional final else clause for if none of the conditions are met.

if (a > 0) {
  printf("Positive");
} elif (a < 0) {
  printf("Negative");
} else {
  printf("Zero is positive?");
}

Variables must be in the same state of definition after a branch has concluded.

let book: Book;
if (nearLibrary) {
  book = loanBook();
} else {
  book = buyBook();
}
// after either possibility
// book is always defined

let book = Book.new();
if (nearLibrary) {
  donate(book);
} else {
  sell(book);
}
// after either possibility
// book is always undefined

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Last update: November 25, 2022