api/classes/qstream

qio

Globals / QStream

Class: QStream<A1, E1, R1>

Represents a sequence of values that are emitted over time.

Type parameters

Name	Default	Description
A1	unknown	The value that would be emitted by this stream.
E1	never	Possible errors that could be thrown by the stream.
R1	unknown	Environment needed to execute this instance. Example: ts import {QStream} from '@qio/core' const s = QStream.of(1, 2, 3).reduce(0, (a, b) => a + b) const runtime = defaultRuntime() runtime.execute(s.drain, console.log) // 6

Hierarchy

• QStream

Index

Constructors

• constructor

Properties

• fold

Accessors

• asArray
• drain
• zipWithIndex

Methods

• chain
• const
• filter
• foldLeft
• foldUntil
• forEach
• forEachWhile
• haltWhen
• haltWhenM
• holdFor
• map
• mapAcc
• mapAccM
• mapM
• merge
• pipe
• scan
• scanM
• take
• toQueue
• zipWith
• const
• fromArray
• fromEffect
• fromEventEmitter
• fromQueue
• interval
• of
• produce
• range
• reject

Constructors

constructor

+ new QStream(fold: <A2, E2, R2>(state: A2, cont: (s: A2) => boolean, next: (s: A2, a: A1) => QIO<A2, E2, R2>) => QIO<A2, E1 | E2, R1 & R2>): QStream

Defined in packages/stream/lib/QStream.ts:197

Constructor to create a new [[Stream]]

Parameters:

Name	Type
fold	<A2, E2, R2>(state: A2, cont: (s: A2) => boolean, next: (s: A2, a: A1) => QIO<A2, E2, R2>) => QIO<A2, E1 \	E2, R1 & R2>

Returns: QStream

Properties

fold

• Readonly fold: <A2, E2, R2>(state: A2, cont: (s: A2) => boolean, next: (s: A2, a: A1) => QIO<A2, E2, R2>) => QIO<A2, E1 | E2, R1 & R2>

Defined in packages/stream/lib/QStream.ts:202

Accessors

asArray

• get asArray(): QIO<A1[], E1, R1>

Defined in packages/stream/lib/QStream.ts:211

Collects all the values from a stream and returns an Array of those values.

Returns: QIO<A1[], E1, R1>

---

drain

• get drain(): QIO<void, E1, R1>

Defined in packages/stream/lib/QStream.ts:216

Returns: QIO<void, E1, R1>

---

zipWithIndex

• get zipWithIndex(): QStream<{ 0: A1 ; 1: number }, E1, R1>

Defined in packages/stream/lib/QStream.ts:222

Adds an index to each value emitted by the current stream.

Returns: QStream<{ 0: A1 ; 1: number }, E1, R1>

Methods

chain

▸ chain<A2, E2, R2>(aFb: (a: A1) => QStream<A2, E2, R2>): QStream<A2, E1 | E2, R1 & R2>

Defined in packages/stream/lib/QStream.ts:228

Flattens the inner stream produced by the each value of the provided stream

Type parameters:

Name
A2
E2
R2

Parameters:

Name	Type
aFb	(a: A1) => QStream<A2, E2, R2>

Returns: QStream<A2, E1 | E2, R1 & R2>

---

const

▸ const<A2>(a: A2): QStream<A2, E1, R1>

Defined in packages/stream/lib/QStream.ts:239

Converts a stream to a constant stream

Type parameters:

Name
A2

Parameters:

Name	Type
a	A2

Returns: QStream<A2, E1, R1>

---

filter

▸ filter(f: (a: A1) => boolean): QStream<A1, E1, R1>

Defined in packages/stream/lib/QStream.ts:245

Creates a new streams that emits values, satisfied by the provided filter.

Parameters:

Name	Type
f	(a: A1) => boolean

Returns: QStream<A1, E1, R1>

---

foldLeft

▸ foldLeft<S2>(seed: S2, fn: (s: S2, a: A1) => S2): QIO<S2, E1, R1>

Defined in packages/stream/lib/QStream.ts:260

Folds a stream into a value.

Type parameters:

Name
S2

Parameters:

Name	Type
seed	S2
fn	(s: S2, a: A1) => S2

Returns: QIO<S2, E1, R1>

---

foldUntil

▸ foldUntil<A2, E2, R2, A3, E3>(state: A2, cont: (s: A2) => boolean, next: (s: A2, a: A1) => QIO<A2, E2, R2>, awt: Await<A3, E3>): QIO<A2, E1 | E2, R1 & R2>

Defined in packages/stream/lib/QStream.ts:267

Folds a stream until the Await is set

Type parameters:

Name
A2
E2
R2
A3
E3

Parameters:

Name	Type
state	A2
cont	(s: A2) => boolean
next	(s: A2, a: A1) => QIO<A2, E2, R2>
awt	Await<A3, E3>

Returns: QIO<A2, E1 | E2, R1 & R2>

---

forEach

▸ forEach<A2, E2, R2>(f: (a: A1) => QIO<A2, E2, R2>): QIO<boolean, E1 | E2, R1 & R2>

Defined in packages/stream/lib/QStream.ts:298

Performs the given effect-full function for each value of the stream

Type parameters:

Name
A2
E2
R2

Parameters:

Name	Type
f	(a: A1) => QIO<A2, E2, R2>

Returns: QIO<boolean, E1 | E2, R1 & R2>

---

forEachWhile

▸ forEachWhile<E2, R2>(f: (a: A1) => QIO<boolean, E2, R2>): QIO<boolean, E1 | E2, R1 & R2>

Defined in packages/stream/lib/QStream.ts:306

Keeps consuming the stream until the effect-full function returns a false.

Type parameters:

Name
E2
R2

Parameters:

Name	Type
f	(a: A1) => QIO<boolean, E2, R2>

Returns: QIO<boolean, E1 | E2, R1 & R2>

---

haltWhen

▸ haltWhen<A3, E3>(awt: Await<A3, E3>): QStream<A1, E1, R1>

Defined in packages/stream/lib/QStream.ts:321

Creates a stream that halts after the Await is set.

Type parameters:

Name
A3
E3

Parameters:

Name	Type
awt	Await<A3, E3>

Returns: QStream<A1, E1, R1>

---

haltWhenM

▸ haltWhenM<A3, E3, R3>(io: QIO<A3, E3, R3>): QStream<A1, E1, R1 & R3>

Defined in packages/stream/lib/QStream.ts:330

Halt the current stream as soon as the io completes.

Type parameters:

Name
A3
E3
R3

Parameters:

Name	Type
io	QIO<A3, E3, R3>

Returns: QStream<A1, E1, R1 & R3>

---

holdFor

▸ holdFor(duration: number): QStream<A1, E1, R1>

Defined in packages/stream/lib/QStream.ts:344

Holds each value for the given duration amount.

Parameters:

Name	Type
duration	number

Returns: QStream<A1, E1, R1>

---

map

▸ map<A2>(ab: (a: A1) => A2): QStream<A2, E1, R1>

Defined in packages/stream/lib/QStream.ts:351

Transforms the values that are being produced by the stream.

Type parameters:

Name
A2

Parameters:

Name	Type
ab	(a: A1) => A2

Returns: QStream<A2, E1, R1>

---

mapAcc

▸ mapAcc<S, A3>(acc: S, fn: (S: S, A: A1) => { 0: S ; 1: A3 }): QStream<A3, E1, R1>

Defined in packages/stream/lib/QStream.ts:360

Like mapAccM but doesn't produce values effectfully.

Type parameters:

Name
S
A3

Parameters:

Name	Type
acc	S
fn	(S: S, A: A1) => { 0: S ; 1: A3 }

Returns: QStream<A3, E1, R1>

---

mapAccM

▸ mapAccM<S, A3, E2, R2>(acc: S, fn: (S: S, A: A1) => QIO<{ 0: S ; 1: A3 }, E2, R2>): QStream<A3, E1 | E2, R1 & R2>

Defined in packages/stream/lib/QStream.ts:371

Effectfully produces new elements using the elements from the current stream and an initial state.

Type parameters:

Name
S
A3
E2
R2

Parameters:

Name	Type
acc	S
fn	(S: S, A: A1) => QIO<{ 0: S ; 1: A3 }, E2, R2>

Returns: QStream<A3, E1 | E2, R1 & R2>

---

mapM

▸ mapM<A2, E2, R2>(f: (a: A1) => QIO<A2, E2, R2>): QStream<A2, E1 | E2, R1 & R2>

Defined in packages/stream/lib/QStream.ts:390

Performs an effect on each value emitted by the stream.

Type parameters:

Name
A2
E2
R2

Parameters:

Name	Type
f	(a: A1) => QIO<A2, E2, R2>

Returns: QStream<A2, E1 | E2, R1 & R2>

---

merge

▸ merge(that: QStream<A1, E1, R1>): QStream<A1, E1, R1>

Defined in packages/stream/lib/QStream.ts:401

Merges two streams.

Parameters:

Name	Type
that	QStream<A1, E1, R1>

Returns: QStream<A1, E1, R1>

---

pipe

▸ pipe<A2, E2, R2>(fn: (a1: QStream<A1, E1, R1>) => QStream<A2, E2, R2>): QStream<A2, E2, R2>

Defined in packages/stream/lib/QStream.ts:427

Pipes the current stream through a function that creates a new Stream.

Type parameters:

Name
A2
E2
R2

Parameters:

Name	Type
fn	(a1: QStream<A1, E1, R1>) => QStream<A2, E2, R2>

Returns: QStream<A2, E2, R2>

---

scan

▸ scan<A3>(acc: A3, fn: (s: A3, a: A1) => A3): QStream<A3, E1, R1>

Defined in packages/stream/lib/QStream.ts:436

Like scanM it creates new values based on some memory.

Type parameters:

Name
A3

Parameters:

Name	Type
acc	A3
fn	(s: A3, a: A1) => A3

Returns: QStream<A3, E1, R1>

---

scanM

▸ scanM<A3, E3, R3>(acc: A3, fn: (s: A3, a: A1) => QIO<A3, E3, R3>): QStream<A3, E1 | E3, R1 & R3>

Defined in packages/stream/lib/QStream.ts:444

Creates a new stream of accumulator values, using an initial accumulator and a function that produces the next set of values.

Type parameters:

Name
A3
E3
R3

Parameters:

Name	Type
acc	A3
fn	(s: A3, a: A1) => QIO<A3, E3, R3>

Returns: QStream<A3, E1 | E3, R1 & R3>

---

take

▸ take(count: number): QStream<A1, E1, R1>

Defined in packages/stream/lib/QStream.ts:453

Emits the first N values skipping the rest.

Parameters:

Name	Type
count	number

Returns: QStream<A1, E1, R1>

---

toQueue

▸ toQueue(capacity: number): Managed<Queue<A1>, E1, R1>

Defined in packages/stream/lib/QStream.ts:467

Converts a Stream into a managed queue

Parameters:

Name	Type	Default value
capacity	number	Number.MAX_SAFE_INTEGER

Returns: Managed<Queue<A1>, E1, R1>

---

zipWith

▸ zipWith<A2, E2, R2, A>(that: QStream<A2, E2, R2>, fn: (A1: A1, A2: A2) => A): QStream<A, E1 | E2, R1 & R2>

Defined in packages/stream/lib/QStream.ts:489

Combines two streams such that only one value from each stream is consumed at a time.

Type parameters:

Name
A2
E2
R2
A

Parameters:

Name	Type
that	QStream<A2, E2, R2>
fn	(A1: A1, A2: A2) => A

Returns: QStream<A, E1 | E2, R1 & R2>

---

const

▸ Staticconst<A1>(a: A1): QStream<A1>

Defined in packages/stream/lib/QStream.ts:34

Creates a stream that constantly emits the provided value.

Type parameters:

Name
A1

Parameters:

Name	Type
a	A1

Returns: QStream<A1>

---

fromArray

▸ StaticfromArray<A1>(t: A1[]): QStream<A1>

Defined in packages/stream/lib/QStream.ts:43

Create a stream from an array

Type parameters:

Name
A1

Parameters:

Name	Type
t	A1[]

Returns: QStream<A1>

---

fromEffect

▸ StaticfromEffect<A1, E1, R1>(io: QIO<A1, E1, R1>): QStream<A1, E1, R1>

Defined in packages/stream/lib/QStream.ts:61

Type parameters:

Name
A1
E1
R1

Parameters:

Name	Type
io	QIO<A1, E1, R1>

Returns: QStream<A1, E1, R1>

---

fromEventEmitter

▸ StaticfromEventEmitter<A>(ev: EventEmitter, name: string): QStream<A>

Defined in packages/stream/lib/QStream.ts:76

Creates a stream of events from an event emitter.

Type parameters:

Name
A

Parameters:

Name	Type
ev	EventEmitter
name	string

Returns: QStream<A>

---

fromQueue

▸ StaticfromQueue<A1>(Q: Queue<A1>): QStream<A1>

Defined in packages/stream/lib/QStream.ts:105

Creates a stream from a Queue

Type parameters:

Name
A1

Parameters:

Name	Type
Q	Queue<A1>

Returns: QStream<A1>

---

interval

▸ Staticinterval<A1>(A1: A1, duration: number): QStream<A1>

Defined in packages/stream/lib/QStream.ts:127

Creates a stream that emits after every given duration of time.

Type parameters:

Name
A1

Parameters:

Name	Type
A1	A1
duration	number

Returns: QStream<A1>

---

of

▸ Staticof<A1>(...t: A1[]): QStream<A1>

Defined in packages/stream/lib/QStream.ts:134

Creates a stream from the provided values

Type parameters:

Name
A1

Parameters:

Name	Type
...t	A1[]

Returns: QStream<A1>

---

produce

▸ Staticproduce<A1, E1, R1>(io: QIO<A1, E1, R1>): QStream<A1, E1, R1>

Defined in packages/stream/lib/QStream.ts:141

Creates a stream by continuously executing the provided IO

Type parameters:

Name
A1
E1
R1

Parameters:

Name	Type
io	QIO<A1, E1, R1>

Returns: QStream<A1, E1, R1>

---

range

▸ Staticrange(min: number, max: number): QStream<number>

Defined in packages/stream/lib/QStream.ts:163

Creates a stream that emits the given ranges of values

Parameters:

Name	Type
min	number
max	number

Returns: QStream<number>

---

reject

▸ Staticreject<E1>(err: E1): QStream<never, E1>

Defined in packages/stream/lib/QStream.ts:195

Type parameters:

Name
E1

Parameters:

Name	Type
err	E1

Returns: QStream<never, E1>