Clojure(script) allows for fast development through functional programming principles like immutable data structures and side effect isolation. It compiles to JavaScript, allowing the same codebase to run on both backend and frontend. The ecosystem includes tools like Fulcro for building single page apps, Clojurescript for compiling to JS, and libraries like Reagent that provide a React-like interface. Well designed data types and comprehensive standard library make Clojure(script) a stable and productive language.

1. Why clojure(script) matters
Claudiu Apetrei - dev at figshare

2. My motivation
www.infocaini.ro
Personal project since 2006
Currently:
python, vanilla coffescript, google app engine
Next version:
Clojure (back-end), Clojurescript (front-end), Fulcro

3. Requirements
- Server side rendering (SEO & user experience)
- Same language on front-end & backend
- Single page app
- Fast development (smarter tooling, ex: google app engine)
- Robust & resilient codebase
- Be productive working 2-3 hours a night
- Understand quickly legacy code after 1-2 months of not working on it
KEEP THINGS AS SIMPLE AS POSSIBLE

4. Work smarter not harder

5. Reselect
Previous stack

6. Javascript is fine as it is :)
Clojurescript
Reason-ml (facebook)
ELM
Purescript
● Functional programming
● Immutable data structures
● Side effects
● Statically typed

7. Damien Katz - couchdb and me

8. OOP The promise and the reality

9. Working with maps, list (data oriented)

10. let a = {
author: {"name": "claudiu"}
};
fun-a1(a);
fun-a2(a);
fun-a3(a);
console.log(a);

12. Programming languages
C family C, C++, Objective-C, C#, Java, PHP, JavaScript, Go, Perl...
LISP family Common Lisp, Clojure, Scheme, Emacs Lisp
ML family ML, Caml, OCaml, F# (haskell inherits from here too)

13. 1

14. 2

15. 3

16. Js history
Eich (Brendan Eich) originally joined intending to put Scheme "in the browser",[6]
but his Netscape superiors insisted that the language resemble Java in terms of
its syntax.

17. One of the best designed languages out there
Clojure is such a well designed language and a pleasure to program in.

18. Clojure language
Lisp dialect
Dynamically typed
Immutable data structures
Data oriented programming

19. Stable, light & complete language
Lisp - “code is data and data is code”
Macros = functions that write code, make it possible to move a lot of
“language features” into libraries
Clojure(script) code from 2015 the same in 2017 (^_^)

20. Macros 1

21. Macros 2

22. Clojure
programming language that targets the JVM (2007)
Clojurescript
compiler that targets javascript (2011)
Awesome host platform interop from day 1.

23. Make use of any existing library
Java or JavaScript (client and nodejs)
Universal(isomorphic)web application
*.clj *.cljs *.cljc

24. Functional programming
Different experience from javascript
Brian Lonsdorf
Oh Composable World!

25. Powerful core data types
All core data types are immutable
Maps are the work-horse in most applications (1% code objects)
:keywords = self referencing functions that can have namespace & value.
(def a {:manuscript/title “x”,
:article/title “y”})

26. Data oriented development
Powerful & well designed data structure
Language core + standard library centered around data manipulation

27. Comprehensive standard library
9/36 chapters completed
already at 400 pages
*only use about 10 - 30 day to day :)

28. Tooling & libs
REPL (read, evaluate, print, loop)
Figwheel (hot-reload)
Google closure compiler
Clojure.spec
Transit
Core.async
Core.match
Test.check
Core.logic
contract system
data format and tools for converting
go style channels for async
pattern matching
property based testing - inspired by haskell
prolog like rational programming

29. Google closure compiler
With clojurescript you get Java GCC + Advanced working out of the box.

30. Clojure.spec
Automatically check every single function call to make sure the arguments are
correct
- More expressive than type system
- Generative testing
- Generate example data
- Unified approach data validation

31. Transit not json
Uses json when possible
Can encode over the wire
- Dates
- Sets
- Lists
- UUIDs
- symbols, keywords, characters
- extensible

32. Clojure ecosystem gems
“Complete story that
removes 60%+ of the
complexity out of my
code.”
Beginner friendly Youtube video series on Fulcro: https://goo.gl/JekurH

33. Fulcro
Sweet spot between framework and library.
- Reactjs wrapper
- State management flow
- Normalised app state
- Support for optimistic updates
- Networking layer
- Backend story with graphql like capabilities
- Co-located css
- ...

34. Interesting community
Experienced like wow “crazy good developers”
X was about to give up on programming as irretrievably* complex when he
found Clojure, which renewed his love for code.
* in a way that cannot be retrieved or put right.

35. Who’s using clojure

36. Codecamp Iasi 24 March 2018, speaker & masterclass
Tony Kay is a software craftsman with nearly 30 years of
experience.
He has published research on concurrent programming,
spent a number of years teaching software
development, and is passionate about software
craftsmanship.
He has worked professionally in C, C++, Java, Scala, Perl,
Javascript, Objective-C, Clojure, and Clojurescript. He is
the lead architect and developer of the web
development library Fulcro, is a contributor to Om Next.

37. Clojure Iasi - meetup.com
- Hang out & help each other on SLACK
- Workshops
- Guest speakers (remote skype/slack)
- Build an open source SPA in Fulcro
https://www.meetup.com/iasi-clojure/
Thank you !

38. Getting started resources
https://www.infoq.com/presentations/Simple-Made-Easy Essence of clojure
https://defn.audio/episodes/2017/11/07/david-nolen.html Clojurescript overview
https://www.packtpub.com/web-development/learning-clojurescript book
https://cursive-ide.com/ editor
https://shaunlebron.github.io/parinfer/ editor plugin for structural editing