Repetition State, Control Flow, and Attributes
You stay in the strip of lane between the gate and the stalls while the first queue thickens. Juniper taps the clipboard against your wrist. "Three beats here. Stop there. Let that one carry."
From this spot you can see Mira stacking trays in careful towers and Tavi counting kettle knocks under his breath, losing count whenever someone speaks to him. You remember queue-keepers at river ferries doing the same work with chalk, bells, and nerves. Now the script needs timing.
@step, [step], and @total
@step is zero-based. [step] is one-based. @total is the full planned count. This is the sort of count Juniper uses when checking whether a repeated cue is landing in the right place.
[rep:3][sep:" | "]{
# Show zero-based step, one-based step, and total planned count.
[cat: @step; "/"; [step]; "/"; @total]
}
0/1/3 | 1/2/3 | 2/3/3
That tiny difference between zero-based and one-based counting matters often enough that it is worth learning early.
@continue and @break
These two charms interrupt the nearest repeater. They are useful when you want to skip or stop a repeated cue without rewriting the whole block.
# Skip the rest of each iteration.
[rep:3]{bell @continue hush}\n
# Stop the repeater the first time it runs.
[rep:3]{bell @break hush}
hushhushhush
hush
With an expression, each charm replaces the repeater's current output with the value on its right.
Protected blocks
At first, you forget the protection wrapper and let one block eat the repetition meant for another.
Wrong attempt
[rep:3]{ hush{bell} }\n
{gong}
What happened
hushbellhushbellhushbell
gong
The first block consumed the repetition setting, so the gong block only ran once.
[rep:3]@{ hush{bell} }\n
{gong}
hushbell
gonggonggong
A protected block starts with @{...}. It keeps attribute changes from leaking and does not consume the caller's attributes.
See also: Protected blocks
Reading and writing attribute state
The mutable attribute keywords have accessor forms too. That means you can store the current pacing rules, tweak them, and read them back when needed.
# Store the current separator, then reuse it.
<@sep = ", ">[rep:3][sep:<@sep>]{wait}
wait, wait, wait
That is the same separator value being written to the current attribute frame and then read back out.
Attribute keyword sugar
The keyword forms are shorter when you only want to affect the next block, which is common when Tavi just wants one quick sound cue.
@rep 3: {tap}\n
@sel "forward": {left|right}
taptaptap
left
Mutators
A mutator receives the current block element as a callback and can decide how to print it.
# Turn each selected element into uppercase before it prints.
@mut [?: elem] { [upper: [elem]] }: {wait}
WAIT
If attributes feel mysterious, the simplest mental model is this: every block grabs the current attribute frame, uses it once, and then resets the consumed values. Protected blocks simply refuse to eat what they were handed.
See also: @mut
More information about repetition state, block attributes, and timing helpers can be found in the Ranty documentation for Attributes, @step, @total, and Blocks.
The queue outside the awnings starts to move like someone meant it to. Juniper stops tapping for a full breath. Then, from the tea stall, Tavi opens his notebook, and you see the next problem at once: the logic works, but the page has turned into brackets all the way down.
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