Portability | portable |
---|---|
Stability | experimental |
Maintainer | forsyde-dev@ict.kth.se |
The synchronuous library defines process constructors and processes for the synchronous computational model. A process constructor is a higher order function which together with combinational function(s) and values as arguments constructs a process.
- mapSY :: (a -> b) -> Signal a -> Signal b
- zipWithSY :: (a -> b -> c) -> Signal a -> Signal b -> Signal c
- zipWith3SY :: (a -> b -> c -> d) -> Signal a -> Signal b -> Signal c -> Signal d
- zipWith4SY :: (a -> b -> c -> d -> e) -> Signal a -> Signal b -> Signal c -> Signal d -> Signal e
- zipWithxSY :: (Vector a -> b) -> Vector (Signal a) -> Signal b
- delaySY :: a -> Signal a -> Signal a
- delaynSY :: a -> Int -> Signal a -> Signal a
- scanlSY :: (a -> b -> a) -> a -> Signal b -> Signal a
- scanl2SY :: (a -> b -> c -> a) -> a -> Signal b -> Signal c -> Signal a
- scanl3SY :: (a -> b -> c -> d -> a) -> a -> Signal b -> Signal c -> Signal d -> Signal a
- scanldSY :: (a -> b -> a) -> a -> Signal b -> Signal a
- scanld2SY :: (a -> b -> c -> a) -> a -> Signal b -> Signal c -> Signal a
- scanld3SY :: (a -> b -> c -> d -> a) -> a -> Signal b -> Signal c -> Signal d -> Signal a
- mooreSY :: (a -> b -> a) -> (a -> c) -> a -> Signal b -> Signal c
- moore2SY :: (a -> b -> c -> a) -> (a -> d) -> a -> Signal b -> Signal c -> Signal d
- moore3SY :: (a -> b -> c -> d -> a) -> (a -> e) -> a -> Signal b -> Signal c -> Signal d -> Signal e
- mealySY :: (a -> b -> a) -> (a -> b -> c) -> a -> Signal b -> Signal c
- mealy2SY :: (a -> b -> c -> a) -> (a -> b -> c -> d) -> a -> Signal b -> Signal c -> Signal d
- mealy3SY :: (a -> b -> c -> d -> a) -> (a -> b -> c -> d -> e) -> a -> Signal b -> Signal c -> Signal d -> Signal e
- sourceSY :: (a -> a) -> a -> Signal a
- filterSY :: (a -> Bool) -> Signal a -> Signal (AbstExt a)
- fillSY :: a -> Signal (AbstExt a) -> Signal a
- holdSY :: a -> Signal (AbstExt a) -> Signal a
- whenSY :: Signal (AbstExt a) -> Signal (AbstExt b) -> Signal (AbstExt a)
- zipSY :: Signal a -> Signal b -> Signal (a, b)
- zip3SY :: Signal a -> Signal b -> Signal c -> Signal (a, b, c)
- zip4SY :: Signal a -> Signal b -> Signal c -> Signal d -> Signal (a, b, c, d)
- zip5SY :: Signal a -> Signal b -> Signal c -> Signal d -> Signal e -> Signal (a, b, c, d, e)
- zip6SY :: Signal a -> Signal b -> Signal c -> Signal d -> Signal e -> Signal f -> Signal (a, b, c, d, e, f)
- unzipSY :: Signal (a, b) -> (Signal a, Signal b)
- unzip3SY :: Signal (a, b, c) -> (Signal a, Signal b, Signal c)
- unzip4SY :: Signal (a, b, c, d) -> (Signal a, Signal b, Signal c, Signal d)
- unzip5SY :: Signal (a, b, c, d, e) -> (Signal a, Signal b, Signal c, Signal d, Signal e)
- unzip6SY :: Signal (a, b, c, d, e, f) -> (Signal a, Signal b, Signal c, Signal d, Signal e, Signal f)
- zipxSY :: Vector (Signal a) -> Signal (Vector a)
- unzipxSY :: Signal (Vector a) -> Vector (Signal a)
- mapxSY :: (a -> b) -> Vector (Signal a) -> Vector (Signal b)
- fstSY :: Signal (a, b) -> Signal a
- sndSY :: Signal (a, b) -> Signal b
Combinational process constructors
Combinational process constructors are used for processes that do not have a state.
mapSY :: (a -> b) -> Signal a -> Signal bSource
The process constructor mapSY
takes a combinational function as argument and returns a process with one input signal and one output signal.
zipWithSY :: (a -> b -> c) -> Signal a -> Signal b -> Signal cSource
The process constructor zipWithSY
takes a combinational function as argument and returns a process with two input signals and one output signal.
zipWith3SY :: (a -> b -> c -> d) -> Signal a -> Signal b -> Signal c -> Signal dSource
The process constructor zipWith3SY
takes a combinational function as argument and returns a process with three input signals and one output signal.
zipWith4SY :: (a -> b -> c -> d -> e) -> Signal a -> Signal b -> Signal c -> Signal d -> Signal eSource
The process constructor zipWith4SY
takes a combinational function as argument and returns a process with four input signals and one output signal.
zipWithxSY :: (Vector a -> b) -> Vector (Signal a) -> Signal bSource
The process constructor zipWithxSY
works as zipWithSY
, but takes a vector of signals as input.
Sequential process constructors
Sequential process constructors are used for processes that have a state. One of the input parameters is the initial state.
The process constructor delaySY
delays the signal one event cycle
by introducing an initial value at the beginning of the output signal.
Note, that this implies that there is one event (the first) at the
output signal that has no corresponding event at the input signal.
One could argue that input and output signals are not fully synchronized,
even though all input events are synchronous with a corresponding output
event. However, this is necessary to initialize feed-back loops.
The process constructor delaynSY
delays the signal n events by introducing n identical default values.
:: (a -> b -> a) | Combinational function for next state decoder |
-> a | Initial state |
-> Signal b | Input signal |
-> Signal a | Output signal |
The process constructor scanlSY
is used to construct a finite state machine process without output decoder. It takes an initial value and a function for the next state decoder. The process constructor behaves similar to the Haskell prelude function scanlSY
and has the value of the new state as its output value as illustrated by the following example.
SynchronousLib> scanldSY (+) 0 (signal [1,2,3,4])
{1,3,6,10} :: Signal Integer
This is in contrast to the function scanldSY
, which has its current state as its output value.
:: (a -> b -> a) | Combinational function for next state decoder |
-> a | Initial state |
-> Signal b | Input signal |
-> Signal a | Output signal |
The process constructor scanldSY
is used to construct a finite state machine process without output decoder. It takes an initial value and a function for the next state decoder. The process constructor behaves similar to the Haskell prelude function scanlSY
. In contrast to the process constructor scanlSY
here the output value is the current state and not the one of the next state.
SynchronousLib> scanlSY (+) 0 (signal [1,2,3,4])
{0,1,3,6} :: Signal Integer
:: (a -> b -> a) | Combinational function for next state decoder |
-> (a -> c) | Combinational function for output decoder |
-> a | Initial state |
-> Signal b | Input signal |
-> Signal c | Output signal |
The process constructor mooreSY
is used to model state machines of "Moore" type, where the output only depends on the current state. The process constructor is based on the process constructor scanldSY
, since it is natural for state machines in hardware, that the output operates on the current state and not on the next state. The process constructors takes a function to calculate the next state, another function to calculate the output and a value for the initial state.
In contrast the output of a process created by the process constructor mealySY
depends not only on the state, but also on the input values.
moore3SY :: (a -> b -> c -> d -> a) -> (a -> e) -> a -> Signal b -> Signal c -> Signal d -> Signal eSource
:: (a -> b -> a) | Combinational function for next state decoder |
-> (a -> b -> c) | Combinational function for output decoder |
-> a | Initial state |
-> Signal b | Input signal |
-> Signal c | Output signal |
The process constructor melaySY
is used to model state machines of "Mealy" type, where the output only depends on the current state and the input values. The process constructor is based on the process constructor scanldSY
, since it is natural for state machines in hardware, that the output operates on the current state and not on the next state. The process constructors takes a function to calculate the next state, another function to calculate the output and a value for the initial state.
In contrast the output of a process created by the process constructor mooreSY
depends only on the state, but not on the input values.
mealy3SY :: (a -> b -> c -> d -> a) -> (a -> b -> c -> d -> e) -> a -> Signal b -> Signal c -> Signal d -> Signal eSource
sourceSY :: (a -> a) -> a -> Signal aSource
The process sourceSY
takes a function and an initial state and generates an infinite signal starting with the initial state as first output followed by the recursive application of the function on the current state. The state also serves as output value.
The process that has the infinite signal of natural numbers as output is constructed by
SynchronousLib> takeS 5 (sourceSY (+1) 0)
{0,1,2,3,4} :: Signal Integer
filterSY :: (a -> Bool) -> Signal a -> Signal (AbstExt a)Source
The process constructor filterSY
discards the values who do not fulfill a predicate given by a predicate function and replaces them with absent events.
Synchronous Processes
The library contains a few simple processes that are applicable to many cases.
zipSY :: Signal a -> Signal b -> Signal (a, b)Source
The process zipSY
"zips" two incoming signals into one signal of tuples.
zip6SY :: Signal a -> Signal b -> Signal c -> Signal d -> Signal e -> Signal f -> Signal (a, b, c, d, e, f)Source
unzipSY :: Signal (a, b) -> (Signal a, Signal b)Source
The process unzipSY
"unzips" a signal of tuples into two signals.
unzip6SY :: Signal (a, b, c, d, e, f) -> (Signal a, Signal b, Signal c, Signal d, Signal e, Signal f)Source
zipxSY :: Vector (Signal a) -> Signal (Vector a)Source
The process zipxSY
"zips" a signal of vectors into a vector of signals.
unzipxSY :: Signal (Vector a) -> Vector (Signal a)Source
The process unzipxSY
"unzips" a vector of signals into a signal of vectors.
mapxSY :: (a -> b) -> Vector (Signal a) -> Vector (Signal b)Source
The process constructor mapxSY
creates a process network that maps a function onto all signals in a vector of signals.