3.24

addOne pid

ghc-pkg 是一个随 GHC 发行的比 cabal-install 底层的包管理工具，用于操作 GHC package database。cabal-install 支持多个 Haskell 编译器，而 ghc-pkg 仅用于 GHC。

ProcessDefinition (Camunda BPM Javadocs 7.9.19-ee)

https://docs.camunda.org/javadoc/camunda-bpm-platform/7.9/org/camunda/bpm/engine/repository/ProcessDefinition.html

编译器注示 pragma


data Point = Point {-# UNPACK #-} !Double
										{-# UNPACK #-} !Double

-funbox-strict-fields编译器

SPECIALIZE可以与INLINE同时使用，INLIEN 有时可以直接加到SPECIALIZE的后面，

此外SPECIALIZE还可以特化类型类实例

chapter23 arrow简介

Arrow类型类

Category类型类，规定了计算过抽象结构中恒值映射与计算之间的复合操作，在Control.Category模块中的定义


class Category cat where
	id :: cat a a
	(.) :: cat b c -> cat a b -> cat a c

ArrowChoice类型类

chapter 24 函数反应式编程简介

Functional Reactive Programming FRP

continuous behavior 连续的行为与离散的事件（discrete event）

24.1 传统的函数反应式编程

连续的行为（continuous behavior）与离散的事件（discrete event）


{-#  lANGUGAGE DeriveFunctor #-}
import Numeric.Integration.TanhSinh
import Control.Applicative

type SampleTime = Double
type StartTime = Double
type Time = Double

data Behavior a = Behavior (StartTime -> SampleTime -> a)
	deriving Functor

instance Applicative Behavior where
	pure a = Behavior (\t0 t1 -> a)
	(<*>) (Behavior fab) (Behavior fa) =
		Behavior (\t0 t1 -> fab t0 t1 (fa t0 t1))

constant :: a -> Behavior a
constant = pure


integration :: Double -> Double -> (Double -> Double) -> Double
integration t0 t1 f = let Result r err eval = absolute (1e-6) (parTrap f t0 t1)

integral :: Behavior Double -> Behavior Double
integral (Behavior beh) = Behavior $ \t0 t1 -> integration t0 t1 (beh t0)

iIntegral :: Double -> Behavior Double -> Behavior Double
iIntegral x b@(Behavior beh) = fmap (+x) (integral b)

integral 是对连续的行为再时间上做积分，iIntegral 是把一个常数值加到积分的计算结果上

reactimate

Yampa