Haskell tutorial(1) -- Introduction to Haskell

1. What functional programming is and what Haskell is

　　What is imperative language?

　　　　--Give a computer sets of tasks and excute it

　　What is Functional Programming?

　　　　--Don't tell a computer what to do but tell it what a stuff you want to excute is

 

　　What is Haskell?

　　　　Haskell is a purely functional programming.

 

2. Properties of Functional programming.

　　(1). Function has not side effects.

　　　　The only thing a function can do is calculate something and return it as a result. One consequence of absence of side effect is Single assignment: A defined 　　variable can not be redefined.

　　(2). Lazy execution

　　　　Functions will not be executed and calculated until its really need to be shown.