The true power of the State ADT really shows when we start combining our discrete, stateful transactions. We start looking at another construction helper named of, used to lift any given value of any type into the resultant. We also explore another i…

We explore a means to represent the combination of our stateful computations using familiar composition. We dive into what makes this possible by talking about what are known as Kleisli Arrows and explore some interesting properties surrounding them.…

When building our stateful computations, there will come a time when we’ll need to combine two or more state transactions at the same time to come up with a new result. Usually this occurs when want to use plain ol’ JavaScript functions with two or m…

我们经常提到函数式编程就是F[T].这个F可以被视为一种运算模式.我们是在F运算模式的壳子内对T进行计算.理论上来讲,函数式程序的运行状态也应该是在这个运算模式壳子内的,也是在F[]内更新的.那么我们就应该像函数式运算T值一样,也有一套函数式更新程序状态的方法.之前我们介绍了Writer Monad.Writer也是在F[]内维护Log的,可以说是一种状态维护方式.但Writer的Log是一种Monoid类型,只支持Semigroup的a|+|b操作,所以只能实现一种两段Log相加累积这种效果.…

Redux provides a convenient helper for combining many reducers called combineReducer, but it focuses in on specific attributes on our state, making it incompatible with using the State ADT. We would like a way to avoid keeping all of our reducers in…

Many times we need to access and transform state, either in part or in full, to be used when calculating other state transitions. We will look at how we can leverage the get function on the State ADT to read and modify portions of our application sta…

In functional programming, a monad is a design pattern that defines how functions, actions, inputs, and outputs can be used together to build generic types,[1] with the following organization: Define a data type, and how values of that data type are…

Lifting Now, let's review map from another perspective. map :: (T -> R) -> [T] -> [R] accepts 2 parameters, a function f :: T -> R and a list list :: [T]. [T] is a generic type paramterized by T, it's not the same as T, but definitely shares s…

Stateful computations require the ability for their state to change overtime. We take a look on one way to replace the state portion of our stateful datatype with a value. We explore the mechanics of how this can be accomplished and introduce the put…

1. Functional programming treats computation as the evaluation of mathematical and avoids state and mutable data. Scala encourages an expression-oriented programming(EOP) 1) In expression-oriented programming every statement is an expression. A state…