Can someone clarify what this Joel On Software quote means: (functional programs have no side effect

Posted by Bob on Stack Overflow See other posts from Stack Overflow or by Bob
Published on 2010-03-15T20:57:08Z Indexed on 2010/03/15 21:09 UTC
Read the original article Hit count: 385

Filed under:

functional-programming

I was reading Joel On Software today and ran across this quote:

Without understanding functional programming, you can't invent MapReduce, the algorithm that makes Google so massively scalable. The terms Map and Reduce come from Lisp and functional programming. MapReduce is, in retrospect, obvious to anyone who remembers from their 6.001-equivalent programming class that purely functional programs have no side effects and are thus trivially parallelizable.

What does he mean when he says functional programs have no side effects? And how does this make parallelizing trivial?

Related posts about functional-programming

Introducing functional programming constructs in non-functional programming languages

as seen on Programmers - Search for 'Programmers'
This question has been going through my mind quite a lot lately and since I haven't found a convincing answer to it I would like to know if other users of this site have thought about it as well. In the recent years, even though OOP is still the most popular programming paradigm, functional programming… >>> More
Functional programming constructs in non-functional programming languages

as seen on Programmers - Search for 'Programmers'
This question has been going through my mind quite a lot lately and since I haven't found a convincing answer to it I would like to know if other users of this site have thought about it as well. In the recent years, even though OOP is still the most popular programming paradigm, functional programming… >>> More
Does functional programming mandate new naming conventions?

as seen on Stack Overflow - Search for 'Stack Overflow'
I recently started studying functional programming using Haskell and came upon this article on the official Haskell wiki: How to read Haskell. The article claims that short variable names such as x, xs, and f are fitting for Haskell code, because of conciseness and abstraction. In essence, it claims… >>> More
pitfalls/disadvantages of functional programming

as seen on Stack Overflow - Search for 'Stack Overflow'
When would you NOT want to use functional programming? What is it not so good at? I am more looking for disadvantages of the paradigm as a whole, not things like "not widely used", or "no good debugger available". Those answers may be correct as of now, but they deal with FP being a new concept (an… >>> More
Should functional programming be taught before imperative programming?

as seen on Stack Overflow - Search for 'Stack Overflow'
It seems to me that functional programming is a great thing. It eliminates state and makes it much easier to automatically make code run in parallel. Many programmers who were first taught imperative programming styles find it very difficult to learn functional programming, because it is so different… >>> More

Developer IT

Can someone clarify what this Joel On Software quote means: (functional programs have no side effect - Developer IT

Can someone clarify what this Joel On Software quote means: (functional programs have no side effect

functional-programming

Related posts about functional-programming

Introducing functional programming constructs in non-functional programming languages

Functional programming constructs in non-functional programming languages

Does functional programming mandate new naming conventions?

pitfalls/disadvantages of functional programming

Should functional programming be taught before imperative programming?

Categories cloud