Tech Talk #4 : Functional Reactive Programming - Đặng Thái Sơn
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Transcript of Tech Talk #4 : Functional Reactive Programming - Đặng Thái Sơn
Reactive Thinking
fb.me/dangthaison.91 | @dangthaison91
FunctionalReactive
Programming
1. What is FRP?
Functional+
Reactive
Microsoft Excel
a = b + c
FRP: Streams of values over time
Core of FRP is Signal
Signal emits value over the
time
FRPis
Declarative
Imperative
Write correct sequence of codes in the correct order. Step by step. (How)
Declarative
Write code to describes what you want to do.
2. Why is FRP?
Example 1
Search API as you type but:
- Don't spam API server every seconds- Only make request if keyword changed- Cancel previous requests
Imperative
Declarative
Example 2
When the user starts simultaneously panning and rotating an object, start a countdown from 3.
Stop the timer either when the countdown ends or when the user stops the gestures.
Imperative
Imperative
Imperative
- When the user touches the screen - Check if a user is panning an object, store that information - Check if both gestures are running simultaneously - start a timer, from 3, counting down. - Check if the user is rotating an object, store that information - Check if both gestures are running simultaneously - start a timer, from 3, counting down. - Check if the user stopped panning - Stop the timer if needed - Check if the user stopped rotating - Stop the timer if needed
- When the timer ticks, decrease the number of seconds left - If the number of seconds left is zero, stop the timer*
There is a Better Way!
Declarative
Declarative
Declarative
Declarative
Declarative
Declarative
Define condition “simultaneously `panning` and `rotating`”Define condition “start a countdown from `3`”Define condition “when the user stops the gestures”Define what a timer is
When the user starts simultaneously `panning` and `rotating` an object, start a countdown from `3`.Stop the timer either when the countdown ends or when the user stops the gestures.”
Advantages• Code more concise & clear, easy to
understand without context
• Readability, highly express
• Make Asynchronous easier
• UI Binding
• Maintainability, Extensibility...
Imperative
Declarative
What we can do• Observables
• Transformations
• Composition
• Combination
• Filter
• Buffer...
Denial• FRP is hard, imperative is more easier
• FRP just is trend!
• Just another Framework
• Unnecessarily complex
3. Thinking in Reactive
FRP is hard, but it is SIMPLE
Imperative is EASY
Simplevs
Easy
Complexity
Simple made Easy— Rick Hickey
FRP is good Trend
Functional Reactive will be
RADIOACTIVE
More: https://goo.gl/lfNWlJBlog: https://dangthaison91.wordpress.com
Thank you!
