An exhaustible source of values

recv returns Nothing if the source is exhausted

An exhaustible sink of values

send returns False if the sink is exhausted

Convert an Input to a Producer

fromInput terminates when the Input is exhausted.

Convert an Output to a Consumer

toOutput terminates when the Output is exhausted.

Spawn a mailbox using the specified Buffer to store messages

Using send on the Output

• fails and returns False if the mailbox is sealed, otherwise it:
• retries if the mailbox is full, or:
• adds a message to the mailbox and returns True.

Using recv on the Input:

• retrieves a message from the mailbox wrapped in Just if the mailbox is not empty, otherwise it:
• retries if the mailbox is not sealed, or:
• fails and returns Nothing.

If either the Input or Output is garbage collected the mailbox will become sealed.

Like spawn, but also returns an action to manually seal the mailbox early:

(output, input, seal) <- spawn' buffer
...

Use the seal action to allow early cleanup of readers and writers to the mailbox without waiting for the next garbage collection cycle.

withSpawn passes its enclosed action an Output and Input like you'd get from spawn, but automatically seals them after the action completes. This can be used when you need the sealing behavior available from 'spawn\'', but want to work at a bit higher level:

withSpawn buffer $ \(output, input) -> ...

withSpawn is exception-safe, since it uses bracket internally.

Buffer specifies how to buffer messages stored within the mailbox

Store an unbounded number of messages in a FIFO queue

Store a bounded number of messages, specified by the Int argument

Only store the Latest message, beginning with an initial value

Latest is never empty nor full.

Like Bounded, but send never fails (the buffer is never full). Instead, old elements are discard to make room for new elements