NAME

SupplyTimeWindow - time-windowed arrays from a Supply

SYNOPSIS

use SupplyTimeWindow;

my $s = Supplier.new;
my $t = $s.Supply.time-window: 1;

start react whenever $t { .say }

for ^10 -> $i { $s.emit: $i; sleep .5.rand }

Window transforms:

# emit the count of items in the last second
$s.Supply.time-window(1, :transform(*.elems)).tap(*.say);

# emit the sum of the last 2 seconds
$s.Supply.time-window(2, :transform(*.sum)).tap(*.say);

DESCRIPTION

SupplyTimeWindow augments all Raku Supply objects with a time-window method. Given a window size in seconds, it emits on every upstream event an Array containing all values whose event timestamp lies within the interval [now - $seconds, now]. Windows are computed from arrival time using now (an Instant), and are sliding rather than tumbling.

METHODS

`method time-window($seconds --> Supply)`

Parameters: $seconds (Numeric > 0), window length in seconds.
Returns: Supply that emits Array of recent values each time the source emits.
Behavior: The first emission is [value]. Subsequent emissions contain the current value plus those still within the last $seconds.

`method time-window($seconds, :&transform! --> Supply)`

Parameters: $seconds and mandatory :transform callable (Callable).
Returns: Supply that emits the result of applying transform to each window array.
Usage: Pass any callable; examples include *.sum, *.elems, or a block.

NOTES

Window membership uses (last_timestamp - $seconds) as the cutoff.
If $seconds is 0, the supply emits single-element arrays (or transform of those).
The method does not buffer or delay upstream events; it computes the window on the fly.
Works with any Supply (e.g., from Supplier, IO events, timers).