Cell

Mutable references that can be concurrently accessed, based on ETS tables.

gleam add cell@1

import cell.{type Cell}

pub fn main() -> Nil {
  let table = cell.new_table()
  let cell: Cell(Int) = cell.new(table)

  // Cells start empty
  assert cell.read(cell) == Error(Nil)

  // They can be written to
  assert cell.write(cell, 1000) == Ok(Nil)
  assert cell.read(cell) == Ok(1000)

  // They can be written to again, to replace the inner value
  assert cell.write(cell, 5) == Ok(Nil)
  assert cell.read(cell) == Ok(5)

  // They can have their value deleted
  //
  // Cells are not garbage collected, so you must always delete their contents
  // when you are finished with them.
  assert cell.delete(cell) == Ok(Nil)
  assert cell.read(cell) == Error(Nil)


  // Other cells can be made with differing types
  let cell2: Cell(String) = cell.new(table)
  assert cell.write(cell2, "Hello!") == Ok(Nil)
  assert cell.read(cell2) == Ok("Hello!")

  // The whole table of cells can be dropped
  cell.drop(table)
  assert cell.read(cell) == Error(Nil)
  assert cell.read(cell2) == Error(Nil)
}

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