Aw: Re: Aw: Functional style programming in python: what will you talk about if you have an hour on this topic?

Rainer Grimm r.grimm at
Sat Jul 16 04:00:40 EDT 2011

Am Samstag, 16. Juli 2011 08:46:42 UTC+2 schrieb Steven D'Aprano:
> Rainer Grimm wrote:
> > I think it's relatively difficult to get a feeling what a are the key
> > points behind functional programming. So I think you should start
> > explaining the concepts behind functional programming. A few ideas.
> > - higher order functions
> > - first class functions
> > - currying
> > - pure functions
> > - list processing
> > - lambda functions
> > - recursion instead of iteration
> > - pattern matching
> Avoiding global state. 
Thats pure functions.
> Lazy data processing, including infinite data streams.
You are right. I forget to mention lazy versus eager evaluation.
> Decorators.
> Iterators.
> Using iterators as a form of pipelining.
Thats special about python adapting functional ideas.
> Some of these might not count as strictly functional in the lambda calculus
> sense, but they're closely related and less academic and more practical.
> > And that should end with the three guys (map, filter and reduce ) as
> > building blocks of functional programming. And that is a good point to
> > introduce list comprehension. Because it's only syntactic sugar for map
> > filter. But what kind of sugar. It's very impressive. Thats my typical way
> > to introduce it in seminars.
> If it were me, I'd probably take a less pure approach and concentrate on
> concrete examples. As far as Python goes, the use of list comps/generator
> expressions, iterators and decorators are the main functional idioms, not
> so much map, filter and especially reduce, which only avoided being removed
> from Python 3 by the narrowest margin.
That is not my point. Before you talk about functional, your audience have to have a feeling, what you are talking about. The problem with functional is, that this expression is very difficult to grab. Like 15 years ago with OO or Design Pattern 10 years ago. I think the ideas behind functional programming are so great, that they a worth to reason a little bit about. Especially for people, that think, each problem can be solved in a OO manner.

But to be honest. I gave a many python seminars in the last years, talking 3
 hours about functional programming in Python and use no pure approach. 
Sorry I answered to fast in my first mail. He asked for functional style programming, not functional programming in Python and doing the whole in one hour. 

Maybe the hour is a good starting point for further investigations.

Greeting from Rottenburg,

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