B03 Clojure Language Basics
- Buy now
- Learn more
Variables and scope

Global Scope
Let and Function Argument Scope
Dynamic Scope
Scope problems diagnosed
Namespaces

Clojure Namespace Declarations
Navigating Namespaces at the REPL
Syntax

for comprehensions
Clojure Function Syntax
Collections

Introduction to Clojure's Collections
Data structures
Vector collection
HashMap collection
Set collection
List collection
Queue collection
Sorted Map collection
Sorted Set collection
Access patterns
Sequential Access Pattern
Remembering Duplicates Access Pattern
Lookup by key Access Pattern
Associate key and value Access Pattern
Dissociate a key and value Access Pattern
Count the elements Access Pattern
Equality Comparison Access Pattern
Removing an item from a set Access Pattern
Splitting a sequence Access Pattern
Containment Check Access Pattern
First-in, first-out Access Pattern
Last-in, First-out Access Pattern
Usage patterns
Entity Usage Pattern
Index Usage Pattern
Tuple Usage Pattern
Multi-comparison Usage Pattern
Transients
Usage in an Atom
Hybrid Collections
Hybrid Types
Vectors and Lists in syntax
Lazy sequences
Collections vs sequences
Lazy sequences

What are lazy sequences?
Gotcha: Effects and chunking
Gotcha: *print-length*
Gotcha: holding onto the head
Gotcha: length checks
The Benefits of Laziness
Destructuring

Introduction
Sequences
Maps Part 1
Maps Part 2
Keyword Arguments
Where to Destructure
Nested Destructuring
Destructuring Examples
Concurrency

Delay
Promise
Future
Deref
Keeping state consistent with Atoms
Sharing state among many threads: Atoms
Ref
Vars
Agents
Locking
Core Async
Threads
ExecutorService
ForkJoin
Reducers
Protocols

What Problems do Clojure Protocols Solve?
How to define protocols
Protocols for Easy Type Conversion
Defining a DSL with Protocols
Building a Component Clone

Namespaces

Namespace declarations can be complicated. They manage all of the dependencies of one namespace on another. There are a lot of options. Would you like to know:

How to choose between :use, :require, and :import
When do you use an apostrophe, and when do you need a vector?
How to make it work with ClojureScript
How to work at the REPL with namespaces
How to import Java classes

Namespaces are required knowledge for working in Clojure and ClojureScript. They can be hard to learn to manage, but once you do, they are rarely a problem.

2 Lessons