handlers

Source: /nix/store/mls72plk3raskl1r5afh3cl9ik3rn969-source/nix/handlers.nix

Module Description

Effect handlers and middleware

Combinators

`via`

Applies a handler to an effect.

A handler is any function that transforms effects, typically Fx<A,U> -> Fx<B,V>. This combinator simply applies the handler, providing a named operation for documentation and readability.

Type Signature

(Fx<A,U> -> Fx<B,V>) -> Fx<A,U> -> Fx<B,V>

Parameters

handler: A function that transforms effects
e: The effect to handle

Example

# Apply a mapping handler
via (map (x: x + 1)) (pure 41)  # => Fx producing 42

# Chain multiple handlers
via (map toString) (via (map (x: x * 2)) (pure 21))

Notes

While via handler e is equivalent to handler e, using via makes the intent clearer and enables future middleware patterns.

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