Scan Operator

scan(::Type{R}, scanFn::F, seed::R) where { R, F <: Function }
scan(scanFn::F) where { F <: Function }

Creates a scan operator, which applies a given accumulator scanFn function to each value emmited by the source Observable, and returns each intermediate result with an optional seed value. If a seed value is specified, then that value will be used as the initial value for the accumulator. If no seed value is specified, the first item of the source is used as the seed.

Arguments

• ::Type{R}: the type of data of transformed value, may be or may not be the same as type of input source
• scanFn::Function: accumulator function with (data::T, current::R) -> R signature
• seed::R: optional initial value for accumulator function

Producing

Stream of type <: Subscribable{R}

Examples

using Rocket

source = from([ 1, 2, 3 ])
subscribe!(source |> scan(+), logger())
;

# output

[LogActor] Data: 1
[LogActor] Data: 3
[LogActor] Data: 6
[LogActor] Completed

using Rocket

source = from([ 1, 2, 3 ])
subscribe!(source |> scan(Vector{Int}, (d, c) -> [ c..., d ], Int[]), logger())
;

# output

[LogActor] Data: [1]
[LogActor] Data: [1, 2]
[LogActor] Data: [1, 2, 3]
[LogActor] Completed

See also: AbstractOperator, RightTypedOperator, ProxyObservable, reduce, logger