mut_cell

This library offers an interior mutability system that manages internal state updates seamlessly, eliminating the need to recache values. Subscribers can register a callback function that is invoked whenever the cell is updated, receiving the new value for immediate use. Unsubscribing is straightforward; a function is provided upon subscription to easily stop receiving updates.

Install

gleam add mut_cell@1

import mut_cell
import gleam/int
import gleam/io

pub fn main() -> Nil {
  // Create a mut_cell
  let icell = mut_cell.make(10)

  // Get the current value
  echo mut_cell.get(icell)

  // Update a mut_cell with a function
  echo mut_cell.update(icell, fn(value) { value * 2 })

  // Create a callback
  let cb = fn(value) { io.println("New value set: " <> int.to_string(value)) }

  // Create a subscriber, which will call our callback
  let sub = mut_cell.subscribe(icell, cb)

  // This operation (and update) will notify subscribers calling their callbacks
  mut_cell.set(icell, 10)

  // Unsubscribe from the mut_cell
  sub()

  // No notifications to send here
  mut_cell.set(icell, 20)

  Nil
}

Further documentation can be found at https://hexdocs.pm/mut_cell.