1 input stream,
seed will be used as an initial accumulation acc
❯When the input stream emits a value v:
- v and the latest acc are given to the
- the returned value is emitted and will be used as the next acc
a new stream of accumulated values
Published on Monday, 5 Feb. 2018
Revised on Monday, 26 Nov. 2018
❚ scan takes three arguments:
- an input stream
- an accumulator function (e.g. prepend a
character to a
- an initial value called seed (e.g.
The accumulator function combines two values:
- an accumulated value called
- and a
As a result, the accumulator returns a
- As you can see, the output stream does not start with the seed. This is how it works, for example, in RxJS.
- In some other reactive stream libraries (like xstream and Most.js) the output stream starts with the seed.
- To start with the seed in RxJS and such, you can chain
❚ startWith(seed) and
❚ scan(f, seed).
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