DavidNolen_TheFunctionalFinalFrontier

8/16/2019 DavidNolen_TheFunctionalFinalFrontier

1/60

Immutability, Interactivity

& JavaScript


2/60

Immutability, Interactivity

& JavaScript

(er ClojureScript)


3/60


4/60


5/60


6/60

Model-View-Controller


7/60

! rst formulated by Trygve Reenskaug

Adele Goldberg and others at Xerox

PARC in 1979

! long shadow, the basic concepts still

prevalent today.


8/60

! At a very abstract level MVC is a sound

separation of concerns

! Implementations leave much to be

desired

! Stateful objects everywhere


9/60


10/60


11/60

Mutable DOM


12/60


13/60


14/60

Functional Programming?

! Functional Reactive Programming

(FRP), still active area of research

! Rx, doesn't address rendering

! Communicating Sequential Processes

(CSP), a coordination language, doesn't

address rendering


15/60


16/60


17/60


18/60

Functional Programming and Data• immutable values, not mutable objects

• “change” returns a new value, leaving the old one unmodified

• they’re persistent

• they’re fast


19/60

Sim le exam le: Linked List

X


20/60


XY


21/60


X

Z

Y


22/60


X

Z

Y

structural sharing


23/60

Sharing structure

• space efficiency

• computational efficiency – avoids copying


24/60

Phil Bagwell

• Array Mapped Trie

• Hash Array Mapped Trie


25/60

Bitmapped Vector Trie

•data lives in the leaves

• e.g. prefix tree used for string lookup

• bitwise trie


26/60

Persistent Vector


27/60

Persistent Vector


28/60

Persistent Vector


29/60

Persistent Vector


30/60

Persistent Vector

108 109 110 111104 105 106 107100 101 102 10396 97 98 99


31/60

Persistent Vector

getindex


32/60

Persistent Vector

108 109 110 111104 105 106 107100 101 102 10396 97 98 99


33/60

Persistent Vector

108 109 110 111104 105 106 107100 101 102 10396 97 98 99

0b01101010


34/60

Persistent Vector

108 109 110 111104 105 106 107100 101 102 10396 97 98 99

0b01101010


35/60

Persistent Vector

108 109 110 111104 105 106 107100 101 102 10396 97 98 99

0b01101010


36/60

Persistent Vector

108 109 110 111104 105 106 107100 101 102 10396 97 98 99

0b01101010


37/60

Persistent Vector

108 109 110 111104 105 106 107100 101 102 10396 97 98 99

0b01101010


38/60

Persistent Vector

assoc


39/60

Persistent Vector

108 109 110 111104 105 106 107100 101 102 10396 97 98 99


40/60

Persistent Vector

108 109 110 111104 105 106 107100 101 102 10396 97 98 99


41/60

Persistent Vector

108 109 110 111104 105 106 107100 101 102 10396 97 98 99


42/60

Persistent Vector

108 109 110 111104 105 106 107100 101 102 10396 97 98 99


43/60

Persistent Vector

108 109 110 111104 105 106 107100 101 102 10396 97 98 99

104 105 foo 107


44/60

Persistent Vector

Length 4 internal vectors?


45/60

Persistent Vector32

From Bagwell, Rompf 2011


46/60

327


47/60

34,359,738,368

elements


48/60

Om


49/60


50/60


51/60

f(D1) = V1


52/60

diff (V0,V1) = CHANGES


53/60


54/60

demo


55/60


56/60

demo


57/60


58/60

Persistent Data Structures … ROCK


59/60


60/60

Questions?

Documents

DavidNolen_TheFunctionalFinalFrontier