Data.IVar.Simple.IChan

An IChans is a type of multicast channel built on top of IVars. It supports multiple readers. The channel is represented as a linked list. The IChan data type represents the head of a channel.

Writing to an IChan head has write-once semantics similar to IVars: only the first of several attempts to write to the head will succeed, returning a new IChan head for writing more values.

Documentation

data IChan a

A channel head

new :: IO (IChan a)

Create a new channel.

read :: IChan a -> [a]

Returns the contents of a channel as a list, starting at the channel head.

This is a pure computation. Forcing elements of the list may, however, block.

write :: IChan a -> a -> IO (IChan a)

Write a single value to the channel.

Raises a BlockedIndefinitelyOnIVar exception if a value has already been written to the channel. Otherwise, returns a new channel head for writing further values.

tryWrite :: IChan a -> a -> IO (Maybe (IChan a))

Attempts to write a single value to the channel.

If a value has already been written, returns Nothing. Otherwise, returns a new channel head for writing further values.