script.md

Script

Clojure

• Quickly ask the audience about the languages they use
• Talk briefly about LISP

What is Clojure?

• Explain how Clojure runs on different environments

Syntax

• Cite Jonh McCarthy's paper: Recursive Functions of Symbolic Expressions and Their Computation by Machine
• Operators can be:
  • Something that resolves to a function
  • Macro
  • Special form

Homoiconicity

• Clojure code is written with data stuctures: lists, vectors, etc
• Explain how this factor is fundamental for the language flexibility
• Touch briefly on macros

Special forms in Clojure and Ruby

• Explain each of the special forms
  • How to bind global vars
  • Simple conditional with if
  • Multiple forms returning one value do
  • Local bindings with let
  • One way to create functions fn
  • Exception handling throw try
  • Clojure's approach to recursion loop recur
• Enphasize on the difference between the amount of special forms in both langs
• Why Ruby has less special forms than Java?
  • Explain why arithimetic operators are not in the list

Syntax demo

• Show how to invoke functions, special forms and macros
• How to create anonnymous functions
• Use apply
• Using quote to create lists and vectors of not binded symbols

Tipos de dados

Literais

• Numbers are:
  • Longs by default
  • Doubles by default
  • Autopromoted to BigInt or BigDecimal
• Strings are:
  • java.lang.String
  • They have all the methods of String
• Characters are:
  • java.lang.Character
  • Share all methods of Character
• Symbols
  • Binded to values or itself
• Keywords
  • Returns itself
  • Reads as itself
  • Equality is fast
  • Useful as keys of Maps
  • Behaves as functions to maps

Non Atomics

• Lists
  • Clojure code is written in terms of them
  • Literal lists must be quoted
  • Fast operation on first and rest
  • Elements are added in front
• Vectors
  • Numerically indexed
  • Fast lookup operations (by index)
• Maps
  • Key/value structure
  • Maps behaves as functions of their keys
    • ({:a "v"} :a) => "v"
  • Anything can be a key
  • Anything can be a value
• Sets
  • Distinct elements
  • Non distinct elements on literal construction throws error

Immutability

• All data types are immutable by default
• Referencial transparency
• Naive implementations of immutable data structures destroys performance

Persistent Data Structures

• All common data is shared

Data types demo

• Show every data type in action
• Maps and keywords as functions

Functions

Sequences

• clojure.lang.Seqable
  • first
  • rest
  • next
  • cons