zudov

Alois Cochard :: Welcome to the Machines

History of data streaming

Problem

We want:

• interleaving effects
• constant space/time
• strong compasability/reusability
• We could try the List, but it doesn’t allow effects
• We could interleave effects via monads (mapM etc), but no constant space/time then and/or lazy IO, meh

zudov

-- | Some exercising for http://okmij.org/ftp/Computation/having-effect.html

module Main where

import Control.Monad.Eff.Console
import Control.Bind (bind)

import Data.Boolean (otherwise)
import Data.Eq ((==))
import Data.Semigroup ((<>))

zudov

I recently read this interesting post about eventual values. One thing that struck me and which I failed to understand is:

• Eventual Values can be interacted with like normal values.
• If an Eventual Value is part of a simple value operation, then that expression resolves to a new Eventual > Value which resolves when all its Eventual Values are resolved.

If I understood the author correctly, that is supposed to be solving several problems:

1. "I don’t know if this is a Promise or not" (I don't know if it's the resolved result of the action, or the action itself).
2. "I’d really like to write code that interacts with values, and not Promises, and leave the machinery to the computer to work out".

zudov

Keybase proof

I hereby claim:

• I am zudov on github.
• I am zudov (https://keybase.io/zudov) on keybase.
• I have a public key ASBCMjt4P9UCqUn1lR9fvFcKdpAqNYRT5c1OX1ZdVmmh6Ao

To claim this, I am signing this object:

zudov

-- | https://jeltsch.wordpress.com/2013/02/14/the-constraint-kind/
{-# LANGUAGE ConstraintKinds, TypeFamilies #-}

import           Prelude hiding (Functor(..))
import           Data.Set    (Set)
import qualified Data.Set as Set
import           GHC.Exts    (Constraint)

class Functor f where
  type Object f a :: Constraint

zudov

Cycle.js approach to handling IO looks similar to how it was done in earlier FRP implementations. That seems to be an independent discovery, and that's always even better.

Yampa provides a function reactimate:

:: IO a	-- ^ IO initialization action
-> (Bool -> IO (DTime, Maybe a)) -- ^ IO input sensing action
-> (Bool -> b -> IO Bool)        -- ^ IO actuaction (output processing) action
-> SF a b	-- ^ Signal function

zudov

module MiniSodium where

import Prelude

import Data.Maybe
import Control.Apply
import Control.Bind

data Stream m a = Stream { sample :: m (Maybe a) }
runStream (Stream s) = s

zudov

package aurelienribon.bodyeditor;

import com.badlogic.gdx.files.FileHandle;
import com.badlogic.gdx.math.Vector2;
import com.badlogic.gdx.physics.box2d.Body;
import com.badlogic.gdx.physics.box2d.CircleShape;
import com.badlogic.gdx.physics.box2d.FixtureDef;
import com.badlogic.gdx.physics.box2d.PolygonShape;
import com.badlogic.gdx.utils.Array;
import com.badlogic.gdx.utils.JsonReader;

zudov

import static com.googlecode.javacv.cpp.opencv_core.cvCopy;
import static com.googlecode.javacv.cpp.opencv_core.cvCreateImage;
import static com.googlecode.javacv.cpp.opencv_core.cvGetSize;
import static com.googlecode.javacv.cpp.opencv_core.cvSetImageROI;
import static com.googlecode.javacv.cpp.opencv_highgui.cvLoadImage;
import static com.googlecode.javacv.cpp.opencv_highgui.cvSaveImage;

import com.googlecode.javacv.cpp.opencv_core.CvRect;
import com.googlecode.javacv.cpp.opencv_core.IplImage;