hourglass.js

Table of Contents

Async

• until
• inspectable 🚧
• retry 🚧
• delay (with jitter) 🚧
• cancelable 🚧
• lazy 🚧
• promisify 🚧
• eta 🚧
• speedBump 🚧
• timeWindow 🚧
• frequency 🚧
• ? mutex 🚧
• timeout 🚧
• concurrent 🚧
• backoff 🚧
• slowStart 🚧
  • inverted backoff

Iterables (Generators, Arrays, ...)

• distinct 🚧
• tee 🚧
• delay 🚧
• observe 🚧
• playback 🚧
• tap 🚧
• roundRobin 🚧
  • interleave https://more-itertools.readthedocs.io/en/stable/api.html#more_itertools.interleave
• unique (distinct) 🚧
• zip 🚧
• collect 🚧
• observe 🚧
• drop
• dropWhile
• takeWhile
• chunk
• count
• slidingWindow
  • https://more-itertools.readthedocs.io/en/stable/api.html#more_itertools.sliding_window
• distribute
  • https://more-itertools.readthedocs.io/en/stable/api.html#more_itertools.distribute
  • distribute into other generators
• padStart
• padEnd
• unique
• flatten
• min
• max
• first
• last
• nth
• sieve

Async Iterables (Streams, Web Streams, Async Generators, ...)

• intoAsyncGenerator 🚧
• distinct 🚧
  • accepts a serializer argument
• filter 🚧
• map 🚧
• reduce 🚧
• delay 🚧
• remember 🚧
• pipe 🚧
• some 🚧
• find 🚧
• every 🚧
• flatMap 🚧
• drop (aka skip) 🚧
• dropWhile
• take 🚧
• enumerate 🚧
• item 🚧
• last 🚧
• roundRobin 🚧
• unique 🚧
• zip 🚧
• collect 🚧
• first 🚧
• throttle 🚧
• debounce 🚧
• merge 🚧

Async

until

Returns a promise that is resolved once the predicate function returns a truthy value, or is rejected if predicate don't reuturn a truthy value before timeout.

Arguments

• predicate: () => boolean
• options
  • options.timeout: number
  • options.interval: number

Returns

Promise<void>

Example

async function isElementMounted() {

}

await until(isElementMounted)

merge

flowchart LR
    s1[a] -.-
    a1("🔴") ---->
    b1("🟠") --->
    c1("🟡") -.->
    end1["🏁"]

    s2[b] -..-
    a2("🟢") -->
    b2("🔵") --->
    c2("🟣") -..->
    end2["🏁"]

    s3["merge(a, b)"] -.-
    a3("🔴") -->
    b3("🟢") -->
    c3("🔵") -->
    d3("🟠") -->
    e3("🟣") -->
    f3("🟡") -.->
    end3["🏁"]

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Example:

const merged = merge(a, b)
await collect(merged) // => ['🔴', '🟢', '🔵', '🟠', '🟣', '🟡']

zip

flowchart LR
    s1[a] -.- a1
    a1("🔴") ----> b1("🟠")
    b1 ---> c1("🟡")
    c1 -.-> d1["🏁"]

    s2[b] -..- a2
    a2("🟢") --> b2("🔵")
    b2 ---> c2("🟣")
    c2 -.-> d2["🏁"]

    s3["zip(a, b)"] -..- a3
    a3("🔴 🟢") ---> b3("🔵 🟠")
    b3("🔵 🟠") ---> c3("🟣 🟡")
    c3 -.-> d3["🏁"]

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take

flowchart LR
    s1[a] -.- a1
    a1("🔴") --> b1("🟠")
    b1 --> c1("🟡")
    c1 --> d1("🟢")
    d1 --> e1("🔵")
    e1 --> f1("🟣")
    f1 -.-> g1["🏁"]

    start3["take(3, a)"] -.- a3
    a3("🔴") --> b3("🟠")
    b3 --> c3("🟡") -.-> end3["🏁"]

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skip(n: number, gen: AsyncGenerator): AsyncGenerator

flowchart LR
    s1[a] -.- a1
    a1("🔴") --> b1("🟠")
    b1 --> c1("🟡")
    c1 --> d1("🟢")
    d1 --> e1("🔵")
    e1 --> f1("🟣")
    f1 -.-> g1["🏁"]

    start3["skip(2, a)"] -...-
    a3("🟡") -->
    b3("🟢") -->
    c3("🔵") -->
    d3("🟣") -.->
    end3["🏁"]

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chain

flowchart LR
    s1[a] -.-
    a1("🔴") -->
    b1("🟠") -->
    c1("🟡") -.->
    end1["🏁"]

    s2[b] -.-
    a2("🟢") -->
    b2("🔵") -->
    c2("🟣") -.->
    end2["🏁"]

    s3["chain(a, b)"] -.-
    a3("🔴") -->
    b3("🟠") -->
    c3("🟡") -->
    d3("🟢") -->
    e3("🔵") -->
    f3("🟣") -.->
    end3["🏁"]

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forward

inspect

inspectCatch

collect

reduce

flowchart LR
    start1[a] -.- a1
    a1("🥖") -->
    b1("🥩") -->
    c1("🥬") -->
    d1("🍅") -->
    e1("🧀") -.->
    end1["🏁"]

    start2["reduce"] -......- a3
    a3("🍔") -.->
    end3["🏁"]

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buffered

chunks

Streams

remember

pipe

const pipeline = pipe(
    gen => filter(x => x % 2 === 0, gen),
    gen => map(x => x * 2, gen)
)
await collect(pipeline(integers)) // => [2, 6, 10, 14]

Reference

• https://docs.rs/futures/0.1.31/futures/stream/trait.Stream.html#method.zip

Design reference

• https://medium.com/@jshvarts/read-marble-diagrams-like-a-pro-3d72934d3ef5