(Strongly Typed) Functional Programming:

A Superior Paradigm?

Two Paradigms

Imperative - abstracted from the hardware

Functional - build on abstract math

Functional: A Continuum

Lowest Common Denominator

Functions as first-class values

and so, higher-order functions

Closures

But to really be functional...

First-class syntax for functions

First-class semantics for functions

The primacy of immutability

Functional Purity

No (implicit) effects

Algebra of types

Pure models of an impure world

So, the Big Question™

Not black and white

Not fanboyism

You want to write VB6?

There are pros and cons, but...

Overall C > Assembly

Overall C# > C

Overall F# > C#

Cons of functional programming

Steep learning curve

Too academic?

Effects are awkward in pure FP

Take Courage

Ongoing learning is not optional

Learn an impure language first

Valuable things cost more

Why do we disdain academics?

Engineers don't disdain physics

Effects may be awkward, but...

Much active R&D on this

You don't need effects as often as you think

You can reap many benefits without being purist

Easy wins in FP

Immutability

Concurrency much simpler

Statelessness

The Simplicity of FP

Less semantic clutter

Less mental clutter

Less syntactic clutter

The Clarity of FP

Obvious correctness

vs

Expressive Power of FP

Types are not only for error prevention

Types model the domain

Comments < Tests < Types

Does FP enable Agility?

Compiler gives more feedback, sooner

Types can prevent stupid errors

Testing versus formal verification

I can't just tell you how good it is

So, no more OOP at all?

Idea #1: Mix & Match

Impure languages are practical

Mixing limits the benefits of FP

Choose your tradeoffs

Idea #2: OO outside, FP inside

OOP is good at modeling processes & state

FP is good at modeling the domain

OO architecture, FP code

Objects = microservices

Unmixed but inclusive

Methods = messages

My Conclusion

Functional programming is a superior paradigm to imperative

Choosing your tool is an exercise in trade-offs

What do you think?