stream-stream-core.nix

Source: /nix/store/mls72plk3raskl1r5afh3cl9ik3rn969-source/nix/stream-core.nix

Module Description

Stream constructors - building streams from values and lists

Combinators

done

Creates a terminated (empty) stream.

Represents the end of a stream - no more elements to produce. This is the base case for stream recursion.

Type Signature

Fx<{}, Step<{}, V>>

Example

eval done.value  # => { more = false; }

See Also

• more - Continue stream with value
• fromList - Create from list (empty list -> done)

fromList

Converts a list to a stream.

Creates a stream that yields each list element in order. Empty list produces a terminated stream.

Type Signature

[V] -> Stream<{}, V>

Parameters

• list: List to convert

Example

runFx (toList (fromList [1 2 3]))  # => [1 2 3]
runFx (fromList [])                # => { more = false; }

See Also

• toList - Convert stream to list
• singleton - Single element stream

more

Creates a stream step with value and continuation.

Produces a stream that yields one value and continues with the next stream. The continuation is not evaluated until needed, enabling lazy, infinite streams.

Type Signature

V -> Stream<S, V> -> Fx<{}, Step<S, V>>

Parameters

• value: Value to yield
• next: Continuation stream (lazy)

Example

more 1 (more 2 (more 3 done))
# Stream of [1, 2, 3]

See Also

• done - Terminate stream
• fromList - Build from list

repeat

Repeats an effect n times as a stream.

Creates a stream that executes the same effect n times, yielding each result. Useful for effectful generation.

Type Signature

Int -> Fx<S, V> -> Stream<S, V>

Parameters

• n: Number of times to repeat
• effect: Effect to execute

Example

runFx (provide 5 (
  toList (repeat 3 state.get)
))  # => [5 5 5]

See Also

• forEach - Execute for each element
• map - Transform elements

singleton

Creates a single-element stream.

Type Signature

V -> Stream<{}, V>

Parameters

• value: Single value to yield

Example

runFx (toList (singleton 42))  # => [42]

See Also

• fromList - Multiple elements
• done - No elements

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