A collection of useful common processes that are useful when plumbing
together a process network. All the processes here rethrow poison when
it is encountered, as this gives the user maximum flexibility (they can
let it propagate it, or ignore it).
The names here overlap with standard Prelude names. This is
deliberate, as the processes act in a similar manner to the
corresponding Prelude versions. It is expected that you will do
import qualified Control.Concurrent.CHP.Common as Common
import qualified Control.Concurrent.CHP.Common as CHP
to circumvent this problem.
|Forever forwards the value onwards, unchanged. Adding this to your process
network effectively adds a single-place buffer.
Forever forwards the value onwards. This is
like id but does not add any buffering to your network, and its presence
is indetectable to the process either side.
extId is a unit of the associative operator Control.Concurrent.CHP.Utils.|->|.
The behaviour of this process was corrected in version 1.1.0 to work properly
when the reader of its output channel was offering choice.
|A process that waits for an input, then sends it out on all its output
channels (in order) during an extended rendezvous. This is often used to send the
output on to both the normal recipient (without introducing buffering) and
also to a listener process that wants to examine the value. If the listener
process is first in the list, and does not take the input immediately, the
value will not be sent to the other recipients until it does. The name
of the process derives from the notion of a wire-tap, since the listener
is hidden from the other processes (it does not visibly change the semantics
for them -- except when the readers of the channels are offering a choice).
|Sends out a single value first (the prefix) then behaves like id.
|Forever reads in a value, and then sends out its successor (using succ).
|Reads in a value, and sends it out in parallel on all the given output
|Forever reads in a value, transforms it using the given function, and sends it
out again. Note that the transformation is not applied strictly, so don't
assume that this process will actually perform the computation. If you
require a strict transformation, use map'.
Like map, but applies the transformation strictly before sending on
Added in version 1.1.0.
|Forever reads in a value, and then based on applying the given function
either discards it (if the function returns False) or sends it on (if
the function returns True).
|Streams all items in a Data.Traversable.Traversable container out
in the order given by Data.Traversable.mapM on the output channel (one at
a time). Lists, Maybe, and Data.Set.Set are all instances
of Data.Traversable.Traversable, so this can be used for all of
|Forever waits for input from one of its many channels and sends it
out again on the output channel.
|Sends out the specified value on the given channel the specified number
of times, then finishes.
|Forever sends out the same value on the given channel, until poisoned.
Similar to the white-hole processes in some other frameworks.
|Forever reads values from the channel and discards them, until poisoned.
Similar to the black-hole processes in some other frameworks.
|Forever reads a value from both its input channels in parallel, then joins
the two values using the given function and sends them out again. For example,
join (,) c d will pair the values read from c and d and send out the
pair on the output channel, whereas join (&&) will send out the conjunction
of two boolean values, join (==) will read two values and output whether
they are equal or not, etc.
Forever reads a pair from its input channel, then in parallel sends out
the first and second parts of the pair on its output channels.
Added in version 1.0.2.
|A sorter process. When it receives its first Just x data item, it keeps
it. When it receieves a second, it keeps the lowest of the two, and sends
out the other one. When it receives Nothing, it sends out its data value,
then sends Nothing too. The overall effect when chaining these things together
is a sorting pump. You inject all the values with Just, then send in a
single Nothing to get the results out (in reverse order).
|Like sorter, but with a custom comparison method. You should pass in
the equivalent of less-than: (<).
A shared variable process. Given an initial value and two channels, it
continually offers to output its current value or read in a new one.
Added in version 1.1.1
A shared variable process. The same as valueStore, but initially waits
to read its starting value before then offering to either output its current
value or read in a new one.
Added in version 1.1.1
|Produced by Haddock version 2.4.2|