Functional Programming in 40 minutes @russolsen Functional - PowerPoint PPT Presentation

Functional Programming in 40 minutes @russolsen

Functional Programming in 40 minutes @russolsen

Functional Programming

Functional Programming Clojure spin

Functional Programming 40 Minutes?

What is it? What's it like? Does it work?

What is it? What's it like? Does it work?

FORGET Everything You Know About Programming

What Do You Know?

Names Name = Value Ifs Iteration Procedures

Strings Numerics Booleans Indentation Names Name = Value Ifs Iteration Procedures

Arrays Hashes Namespaces Strings Numerics Booleans Indentation Names Name = Value Ifs Iteration Procedures

Inheritance Classes Methods Arrays Hashes Namespaces Strings Numerics Booleans Indentation Names Name = Value Ifs Iteration Procedures

Programs Inheritance Classes Methods Arrays Hashes Namespaces Strings Numerics Booleans Indentation Names Name = Value Ifs Iteration Procedures

FORGET REALLY? Everything You Know About Programming

Functional Programming

Refactor Everything You Know About Programming

It Works But...

Mess

What About Programming?

During the type erasure process, the Java compiler erases all type parameters and replaces each with its first bound if the type parameter is bounded, or Object if the type parameter is unbounded. https://docs.oracle.com/javase/tutorial/java/generics/genTypes.html

During the type erasure process, the Java compiler erases all type parameters and replaces each with its first bound if the type parameter is bounded, or Object if the type parameter is unbounded.

Protected methods: a protected method is similar to a private method, with the addition that it can be called with, or without, an explicit receiver, but that receiver is always self (it’s defining class) or an object that inherits from self . https://medium.com/@tjoye20/ruby-access-control-basics-public-vs-private-vs-protected- methods-7788b26e04a7

A friend function of a class is defined outside that class' scope but it has the right to access all private and protected members of the class. Even though the prototypes for friend functions appear in the class definition, friends are not member functions. https://www.tutorialspoint.com/cplusplus/cpp_friend_functions.htm

Programs Inheritance Classes Methods Arrays Hashes Namespaces Strings Numerics Booleans Indentation Names Name = Value Ifs Iteration Procedures

Messy?

Programs Namespaces Arrays Hashes Strings Numerics Booleans Indentation Name = Names Ifs Iteration Value

f(x)

f(x) 2 4 1 6 8 3 4 2 5 10

2 4 1 6 8 3 4 2 5 10

Methods Procedures Subroutines Functions

6 3 5 10

6 3 42 5 10 ??

6 3 5 10

6 3 10 5

A Thing f(x)

A Thing I Can Make f(x)

f(x)

1st Class

Look at Input Produce Output

No Side E ff ects

x = ['a','b','c'] y = a(x) x = ?

x = ['a','b','c'] c(a(x) + b(x)) + d(x) * e(x) - 4 * (q(x) - f(x)) + d(x) * e(x) - 4 * (q(x) - f(x)) + b(x)) + d(x) / c(a(x) + b(x)) + d(x) * e(x) + g(x) + h(x) * y = floor(b(x)) + 16 * a(x) - ceil(g(x) - c(a(x) + b(x)) + d(x) * e(x) - 4 * (q(x) - f(x)) + d(x) * e(x) - 4 * (q(x) - f(x)) + b(x)) + d(x) / c(a(x) + b(x)) + d(x) * e(x) + g(x) + h(x) * floor(b(x)) + 16 * a(x) x = ?

Programs f(x) Namespaces Arrays Hashes Strings Numerics Booleans Indentation Name = Names Ifs Iteration Value

Problem

a b c

a b c

a Q c

x = ['a','b','c'] c(a(x) + b(x)) + d(x) * e(x) - 4 * (q(x) - f(x)) + d(x) * e(x) - 4 * (q(x) - f(x)) + b(x)) + d(x) / c(a(x) + b(x)) + d(x) * e(x) + g(x) + h(x) * y = floor(b(x)) + 16 * a(x) - ceil(g(x) - c(a(x) + b(x)) + d(x) * e(x) - 4 * (q(x) - f(x)) + d(x) * e(x) - 4 * (q(x) - f(x)) + b(x)) + d(x) / c(a(x) + b(x)) + d(x) * e(x) + g(x) + h(x) * floor(b(x)) + 16 * a(x) x = ?

t = c(a(x) + b(x)) + d(x) * e(x) - 4 * (q(x) - f(x)) + d(x) * e(x) - 4 * (q(x) - f(x)) + b(x)) + d(x) / c(a(x) + b(x)) + d(x) * e(x) + g(x) + h(x) * floor(b(x)) + 16 * a(x) - ceil(g(x) x[2] = 'Q' y = t + c(a(x) + b(x)) + d(x) * e(x) - 4 * (q(x) - f(x)) + d(x) * e(x) - 4 * (q(x) - f(x)) + b(x)) + d(x) / c(a(x) + b(x)) + d(x) * e(x) + g(x) + h(x) * floor(b(x)) + 16 * a(x)

t = c(a(x) + b(x)) + d(x) * e(x) - 4 * (q(x) - f(x)) + d(x) * e(x) - 4 * (q(x) - f(x)) + b(x)) + d(x) / c(a(x) + b(x)) + d(x) * e(x) + g(x) + h(x) * floor(b(x)) + 16 * a(x) - ceil(g(x) x[2] = 'Q' y = t + c(a(x) + b(x)) + d(x) * e(x) - 4 * (q(x) - f(x)) + d(x) * e(x) - 4 * (q(x) - f(x)) + b(x)) + d(x) / c(a(x) + b(x)) + d(x) * e(x) + g(x) + h(x) * floor(b(x)) + 16 * a(x)

Immutable

a b c a Q c

Problem

Copies Copies Copies

a b c d e f g h i j k l m n o p q r s t u v w x y z !

m n a b c d e f g h i j k l o p q r s t u v w x y z ! m Q a b c d e f g h i j k l o p q r s t u v w x y z !

Persistent Data Structures

a b c d e f g h i j k l m n o p q r s t u v w x y z !

a b c d e f g h i j k l m n o p q r s t u v w x y z !

m Q o

Q m X o

Q m X o

Q a b c d e f g h i j k l m X o p q r s t u v w x y z !

3

3

Programs f(x) Namespaces Arrays* Hashes* Strings Numerics Booleans Indentation Name = Names Ifs Iteration Value

Problem

Side E ff ects

SIDE EFFECTS Russ Olsen russ@russolsen.com

EFFECTS Russ Olsen russ@russolsen.com

Atoms 57

Atoms f(x) 57

Atoms f(x) 58

Atoms f(x) 59 g(x)

Atoms f(x) 59 g(x) g(x)

Agents/Actors f(x) some_code(queue) g(x)