1.
Киев 2017
Только реальные кейсы. Только актуальные тренды.
Functional Web
Serhiy Kalinets, Steer73
@skalinets
kalinets@gmail.com

2.
Киев 2017
About me
16 years in the business
In .NET since 2005
Love to code
Software Architect
@ Steer73
@skalinets 2

3.
Киев 2017
Current State of .NET Web
Development
@skalinets 3

4.
Киев 2017
ASP.NET (Core)
Web API
Client : JS SPA
@skalinets 4

5.
Киев 2017
Alternatives
NancyFX
Monorail
FubuMVC / Jasper
@skalinets 5

6.
Киев 2017
Problems
Too verbose C# code
Fullstack is hard
OOP
@skalinets 6

7.
Киев 2017
Introducing SAFE
Suave
Azure
Fable
Elmish
@skalinets 7

8.
Киев 2017
Why F#?
Suitable not only for academic /
financial code
Less verbose than c#
Rich ecosystem
Nice for LOB applications
@skalinets 8

9.
Киев 2017
F# has it from start
async
tuples
pattern matching
algebraic types
@skalinets 9

10.
Киев 2017
Suave
Fast non blocking server
Purely functional
Rich feature set
@skalinets 10

11.
Киев 2017
Hello World in Suave
open Suave
startWebServer
defaultConfig
(Successful.OK "Hello, world!")
@skalinets 11

12.
Киев 2017
Hello World in Suave
@skalinets 12

13.
Киев 2017
WebParts
open Suave
startWebServer
defaultConfig
(Successful.OK "Hello, world!")
@skalinets 13

14.
Киев 2017
WebPart
type WebPart = Context ->
Async<Context option>
// C# equivalent
Func<Context, Task<Nullable<Context>>>
@skalinets 14

15.
Киев 2017
Web Parts
Building blocks for suave
application
It’s like OWIN middleware but
more lightweight
Composable
@skalinets 15

16.
Киев 2017
WebParts: Content Providers
OK "Hello, world!"
// returns 200 OK with content
@skalinets 16

17.
Киев 2017
WebParts: Filters
Path "/foo"
// returns None if path does not
// match
GET
// returns None if verb does not
// match
@skalinets 17

18.
Киев 2017
WebParts: Combinators
a >=> b
// returns None if a is None
// otherwise feeds result of a
// into b and returns its result
@skalinets 18

19.
Киев 2017
WebParts: Combinators
choose [a; b]
// returns None if a is None
// otherwise feeds result of a
// into b and returns its result
@skalinets 19

20.
Киев 2017
Config Example
choose
[ GET >=> path "/public" >=> OK "Default GET"
// Access to handlers after this one will require
authentication
Authentication.authenticateBasic
(fun (user,pwd) -> user = "foo" && pwd = "bar")
(choose [
GET>=> path "/whereami"
>=> OK "Hello authenticated person"
GET >=> path "/" >=> dirHome
GET >=> browseHome // Serves file if exists
])]
@skalinets 20

21.
Киев 2017
Suave
Self hosted
WebSockets
Azure Functions
@skalinets 21

22.
Киев 2017
Azure
Just another cloud platform
Is familiar for most .NET guys
@skalinets 22

23.
Киев 2017
Fable
F# -> JS compiler
Supports modern JS frameworks
Same code in API and UI
Interop with JavaScript
@skalinets 23

24.
Киев 2017
F# support
collections
dates
regular expressions
string formatting
observables
async
and even reflection
@skalinets 24

25.
Киев 2017
Fable Repl
@skalinets 25

26.
Киев 2017
Elmish
Based on ELM
Makes fable code
even less verbose
One way, immutable
@skalinets 26

27.
Киев 2017
Elmish Concept
@skalinets 27

28.
Киев 2017
Elmish: The Basics
type Model = int
type Msg =
| Increment
| Decrement
| Reset
@skalinets 28

29.
Киев 2017
Elmish: The Basics
let init () : Model = 0
let update msg model =
match msg with
| Increment -> model + 1
| Decrement -> model - 1
| Reset -> 0
@skalinets 29

30.
Киев 2017
Elmish: The Basics
let view model dispatch =
div
[ ClassName "columns is-vcentered" ]
[ div
[ ClassName "column "
Style [ Width "170px" ] ]
[ str (sprintf "Counter: %i" model) ]
simpleButton "+1" Increment dispatch
simpleButton "-1" Decrement dispatch
simpleButton "Reset" Reset dis patch ]
@skalinets 30

31.
Киев 2017
@skalinets 31

32.
Киев 2017
Developer Experience
While visual studio can be used for
development, there are other,
usually better alternatives
@skalinets 32

33.
Киев 2017
IDE: Visual Studio Code
Nice lightweight IDE
Many various extensions
Ionide – extension for F#
@skalinets 33

34.
Киев 2017
Acceptance Tests: canopy
F# wrapper around WebDriver
Very nice syntax
Can be understood
by
non-developers
@skalinets 34

35.
Киев 2017
Testcase
Open url http://site.com
Enter “Minnie” as First Name
Select Female Gender
Click “Continue”
Verify that First Name is “Minnie”
@skalinets 35

36.
Киев 2017
Executable Testcase
url "http://site.com"
"#firstName" << "Minnie"
click "#genderFemale"
click "Continue"
"First Name" == "Minnie"
@skalinets 36

37.
Киев 2017
Package Manager: paket
Nuget on steroids
Less xml
No more nuget hell
@skalinets 37

38.
Киев 2017
nuget.org is aware
@skalinets 38

39.
Киев 2017
Build: Fake
Reach feature set
Nice syntax
Functional
@skalinets 39

40.
Киев 2017
Continuous Development
Continuous unit testing (VS
Code + expecto)
Hot reload in browser,
like JS hipsters
@skalinets 40

41.
Киев 2017
@skalinets 41

42.
Киев 2017
SAFE Sample: Book Store
@skalinets 42

43.
Киев 2017
SAFE is not all-or-nothing
You can use alternative
application architectures
utilizing elements of SAFE
stack in different ways
@skalinets 43

44.
Киев 2017
Typical SAFE stack
https://compositional-it.com/blog/2017/09-22-safe-release/index.html
@skalinets 44

45.
Киев 2017
Alternative SAFE stack
https://compositional-it.com/blog/2017/09-22-safe-release/index.html
@skalinets 45

46.
Киев 2017
Partial SAFE stack
https://compositional-it.com/blog/2017/09-22-safe-release/index.html
@skalinets 46

47.
Киев 2017
On-Premise partial SAFE stack
https://compositional-it.com/blog/2017/09-22-safe-release/index.html
@skalinets 47

48.
Киев 2017
Lite SAFE stack
https://compositional-it.com/blog/2017/09-22-safe-release/index.html
@skalinets 48

49.
Киев 2017
Try it yourself
@skalinets 49

50.
Киев 2017
Thanks!
@skalinets
kalinets@gmail.com
skalinets.github.io
@skalinets 50