Functional Programming With JavaScript
My name is Luke
And I like JavaScript
lwestby@alumni.nd.edu
@luke_dot_js
What do I mean by Functional Programming?
f: X \rightarrow Y
f:X→Y
In functional programming, functions act like this
They represent transformations on values
Functions can both transform values and be transformed as values
(first-class functions)
This allows us to consider sets of higher-order functions which apply transformations to data
Let me propose a definition
A Collection is
- A grouping of stuff
- Always defined
- Iterable
- Possibly (but not always) empty
- Possibly (but not always) infinite
Challenge #1:
Start thinking about values in terms of collections
What JavaScript values are collections?
- Arrays
- Objects
- Maps and Sets
What JavaScript values are not collections?
- Numbers, Booleans, and Symbols
- undefined
- null
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Any questions so far?
Challenge #2:
Start thinking about everything in terms of collections
Collections can be expressed over time
-
mousemove events can be expressed as a collection of mouse positions over time
-
XHRs can be expressed as a collection of server side values that arrive over time
-
Many, many, many more possibilities
This perspective allows us to approach UI events, XHR, etc. the same way we approach arrays and objects
