varying 0.1.0.1 → 0.1.0.2

raw patch · 2 files changed

+86/−1 lines, 2 files

Files

• README.md +82/−0
• varying.cabal +4/−1

@@ -0,0 +1,82 @@+# varying+This library provides automaton based varying values useful for both functional+reactive programming (FRP) and locally stateful programming (LSP). It is +influenced by the [netwire](http://hackage.haskell.org/package/netwire) and +[auto](http://hackage.haskell.org/package/auto) packages. Unlike netwire the +concepts of inhibition and time are explicit (through `Control.Varying.Event` +and `Control.Varying.Time`) and the library aims at being minimal and well +documented with a small API surface area.++Depending on your types and values varying can provide discrete or continuous+time semantics.++## Getting started++```haskell+module Main where++import Control.Varying+import Control.Varying.Time as Time -- time is not auto-exported+import Text.Printf++-- | A simple 2d point type.+data Point = Point { x :: Float+                   , y :: Float+                   } deriving (Show, Eq)++-- | Our Point value that varies over time continuously in x and y.+backAndForth :: Var IO a Point+backAndForth =+    -- Here we use Applicative to construct a varying Point that takes time+    -- as an input.+    (Point <$> tweenx <*> tweeny)+        -- Here we feed the varying Point a time signal using the 'plug left'+        -- function. We could similarly use the 'plug right' (~>) function+        -- and put the time signal before the Point. This is needed because the+        -- tweens take time as an input.+        <~ time++-- An exponential tween back and forth from 0 to 100 over 2 seconds.+tweenx :: Monad m => Var m Float Float+tweenx =+    -- Tweens only happen for a certain duration and so their sample+    -- values have the type (Ord t, Fractional t => Event t). After construction+    -- a tween's full type will be+    -- (Ord t, Fractional t, Monad m) => Var m t (Event t).+     tween easeOutExpo 0 100 1+         -- We can chain another tween back to the starting position using+         -- `andThenE`, which will sample the first tween until it ends and then+         -- switch to sampling the next tween.+         `andThenE`+             -- Tween back to the starting position.+             tween easeOutExpo 100 0 1+                 -- At this point our resulting sample values will still have the+                 -- type (Event Float). The tween as a whole will be an event+                 -- stream. The tween also only runs back and forth once. We'd+                 -- like the tween to loop forever so that our point cycles back+                 -- and forth between 0 and 100 indefinitely.+                 -- We can accomplish this with recursion and the `andThen`+                 -- combinator, which samples an event stream until it+                 -- inhibits and then switches to a normal value stream (a+                 -- varying value). Put succinctly, it disolves our events into+                 -- values.+                 `andThen` tweenx++-- A quadratic tween back and forth from 0 to 100 over 2 seconds.+tweeny :: Monad m => Var m Float Float+tweeny =+    tween easeOutQuad 0 100 1 `andThenE` tween easeOutQuad 100 0 1 `andThen` tweeny++-- Our time signal.+time :: Var IO a Float+time = deltaUTC++main :: IO ()+main = do+    putStrLn "Varying Values"+    loop backAndForth+        where loop :: Var IO () Point -> IO ()+              loop v = do (point, vNext) <- runVar v ()+                          printf "\nPoint %03.1f %03.1f" (x point) (y point)+                          loop vNext+```

@@ -10,7 +10,7 @@ -- PVP summary:      +-+------- breaking API changes --                   | | +----- non-breaking API additions --                   | | | +--- code changes with no API change-version:             0.1.0.1+version:             0.1.0.2  -- A short (one-line) description of the package. synopsis:            Automaton based varying values, event streams and tweening.@@ -50,6 +50,9 @@  -- Constraint on the version of Cabal needed to build this package. cabal-version:       >=1.10++extra-source-files:  README.md+  source-repository head   type:     git