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understanding clo ure through data
James Reeves @weavejester boolean·knot
disclaimer
I'll be telling a few lies
understanding clo ure j through data James Reeves @weavejester - - PowerPoint PPT Presentation
understanding clo ure j through data James Reeves @weavejester - - PowerPoint PPT Presentation
understanding clo ure j through data James Reeves @weavejester booleanknot disclaimer I'll be telling a few lies disclaimer I'll be telling a few lies simplifications j clo ure a functional programming language a lisp (more on
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disclaimer
I'll be telling a few lies
simplifications
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clo ure j
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a functional programming language a lisp
(more on that later)
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- fficially targets Java
(Clojure) .NET (ClojureCLR) javascript (ClojureScript)
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first released in September 2007 by Rich Hickey
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let's start with edn
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extensible data notation
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edn ⊆ clojure json ⊆ javascript
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json edn
3.14159 3.14159 "hello world" "hello world" [1, 2, 3, 4] [1 2 3 4] {"name": "alice"} {"name" "alice"} true true null nil
numbers strings vectors maps booleans nil
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json
[1 2 3]
array
- rdered, random access
collections
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edn
[1 2 3] (1 2 3) #{1 2 3}
vector list set
- rdered, random access
- rdered
unordered, distinct
collections
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json
"name"
string text data and identifier
identifiers
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edn
"name" :name name
string keyword symbol text data references itself references something else
identifiers
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example
{:name "Alice" :sex :female :job cryptographer}
universal definition might reference job description, benefits, etc
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namespaces
mammal.canine/dog :status/ready
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tags
"f81d4fae-7dec-11d0-a765-00a0c91e6bf6" "1985-04-12T23:20:50.52Z" #inst #uuid
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tags
#color/rgb "e8a433" #color/rgb [232 164 51]
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what's the connection to clojure?
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clojure = edn + eval
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evaluation
most data evaluates to itself
"foo" "foo" 123 123
eval
[1 2 3] [1 2 3] {:x 1} {:x 1}
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evaluation
symbols evaluate to a bound value
pi 3.14159
eval
message "Hello World"
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evaluation
lists evaluate based on their first element
(+ 1 1) 2
eval
(and true false) false
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evaluation
functions evaluate their arguments
(+ (* 3 3) (* 4 4)) ⇒ (+ 9 16) ⇒ 25
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evaluation
macros evaluate their return value
(postfix (9 16 +)) ⇒ (+ 9 16) ⇒ 25
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homoiconic
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homo · iconic
the same representation
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homo · iconic
writing code with data
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clojure data
♥
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why such a close relationship?
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macros allow us to add new syntax through libraries
core.async core.logic core.typed async programming logic programming static typing
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but is that the only reason?
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“Simple Made Easy”
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simple complex
why?
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simple complex
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complexity ≠ cardinality
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complexity = interlacing coupling connections
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how do we usually deal with complexity?
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{ }
mutable state
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{ }
mutable state
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{ }
- bject
encapsulates state
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- bject
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methods
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encapsulation isolates complexity
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defensive strategy
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what would an offensive strategy look like?
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can something have zero complexity?
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immutable values
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mutable state needed for
- 1. performance
- 2. communication across threads
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{ }
- bject
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do we need encapsulation?
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walls are expensive
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{ }
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can we do that?
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in distributed environments we
- ften work with immutable values
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are there any immediate benefits?
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free API
getters setters serialisation transversal transformations equality diffing merging deserialisation lensing auditing concurrency
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