FRP.Timeless.Prefab.Discrete

Discrete Signals

occursFor

Arguments

:: Monad m

=> b

Constant Output

-> Int

Number of sample periods

-> Signal s m a b

Produces output for a several sample periods, then inhibits.

Typical usage:

() `occursFor` 1 >>> <some IO actions> >>> snapOnce

The example above will perform the IO action once and then hold the result forever

impulse :: Monad m => b -> Signal s m a b

A value that appears for a semantically infinitely short period of time

oneShot :: Monad m => b -> Signal s m a b

snapOnce :: Monad m => Signal s m a a

Takes the snapshot of the value when signal is activated, and then holds value forever

Typical usage:

() `occursFor` 1 >>> <some IO actions> >>> snapOnce

The example above will perform the IO action once and then hold the result forever

inhibitsAfterPeriods :: Int -> Signal s m a a

Acts as identity for a several sample periods, then inhibits.

runAndHold :: Monad m => Signal s m a b -> Signal s m a b

Runs a signal once and hold the result forever.

It is a combination of inhibitsAfter and snapOnce

Logic Signals

rising

Arguments

:: Monad m

=> Bool

Initial value

-> Signal s m Bool Bool

Rising edge filter. Creates an impulse at rising edge

falling

Arguments

:: Monad m

=> Bool

Initial value

-> Signal s m Bool Bool

Falling edge filter. Creates an impulse at falling edge

edge

Arguments

:: Monad m

=> Bool

Initial value

-> Signal s m Bool Bool

Edge filter. Creates an impulse at edge

latch

Arguments

:: Monad m

=> Bool

Initial value

-> Signal s m (Bool, Bool) Bool

A Set-Reset latch, with the first input set, second input reset. Current output value has higher priority (Prefer lazy!)

latchS :: Monad m => Signal s m Bool Bool

A set-latch whose initial value is False, but turns True and holds when its input becomes true

latchR :: Monad m => Signal s m Bool Bool

A reset-latch whose initial value is True, but turns False and holds when its input becomes false