Conditions and loops

[if], [elif], [else]

[if] plays the block indented under it only when its condition is true. [elif] gives another condition to try when the ones before it failed, and [else] is played when none of them held.

:= shop
[let $gold = 12]
[if $gold >= 10]
    Merchant: The lantern is yours.
    [let $gold = $gold - 10]
[elif $gold > 0]
    Merchant: Not quite enough, come back later.
[else]
    Merchant: Come back when you can pay.
Merchant: Goodbye.
---

[elif] and [else] are written at the indentation of the [if] they belong to, and [else] comes last.

A condition has to be a boolean: [if $gold] is an error when $gold is a number, write [if $gold > 0].

[while]

[while] repeats its block as long as its condition is true.

:= start
[let $gold = 0]
[while $gold < 3]
    [let $gold = $gold + 1]
    Alice: I have [$gold] coins.
Alice: That will do.
---

Inside the block, [break] leaves the loop and [continue] goes straight to the next turn. Both act on the innermost [while], and can be nested in a condition or in a choice:

:= start
[let $turn = 0]
[while true]
    [let $turn = $turn + 1]
    Alice: Turn [$turn]. One more?
    -> Yes
        [continue]
    -> No
        [break]
Alice: Done.
---

A dialogue that runs for too long without anything to show is stopped with an error, so a loop that never ends cannot freeze the game.