1. Hackathon
WiFi pass: groundfloorsv
Download Opa 1.0.5 at opalang.org
while bandwidth lasts

2. Problem #1

3. Problem #1
Memcache Framework
Web Browser
Web Browser
Web Browser
Web Browser Web
Web Browser Web
Web
Web Browser
Web Browser Server Language
Language
Web Browser
Web Browser Server
Server Language
Web Browser Language
Web Browser
Web Browser Web Server
Web Browser
Web Browser
Web Browser
Web Browser
Web Browser
Web Browser
Web Browser ORM
Web Browser
Web Browser
Web Browser
Web Browser
Web Browser
Web Browser Database
Web Browser
Web Browser Database
Database
Web Browser
Web Browser Database
Database
Web Browser
Web Browser
Web Browser
Web Browser Database
Web Browser

5. Universal Language

6. Universal Language

7. Universal Language

8. Universal Language

9. Universal Language

10. Problem #2

11. This is JavaScript
> 9 + 5 + “ customers”
14 customers
> “Customers: ” + 9 + 5
Customers: 95

12. < ?

13. This is JavaScript
switch (x) {
case 0:
if (x == 0) retry();
retry(); break;
else if (x == 1) case 1:
success(); success();
else break;
error(); default:
error();
}

14. x = “0”
switch (x) {
case 0:
if (x == 0) retry();
retry(); break;
else if (x == 1) case 1:
success(); success();
else break;
error(); default:
error();
}
retry error

15. This is JavaScript
[] + []
[] + {}
{} + []
{} + {}
(@garybernhardt)

16. This is JavaScript
[] + [] = ““
[] + {} = {}
{} + [] = 0
{} + {} = NaN
(@garybernhardt)

22. Project Launch: June 21st 2011
Man-years: 60+

26. Code automation

27. AJAX/COMET
Code automation Non-blocking
Event-driven

29. Code verification

30. Code verification

31. Code verification

32. Live Demo

33. JS-like syntax
HTML first class
Event-driven

35. Code verification

36. Code verification

37. Code verification

38. Live Demo

39. mo
De de
ive hi
L o
T
// try different typing errors:
// show errors in the terminal
// show type infered
function foo(s) {
String.length(s);
}
function bar(x, y) {
foo(x) + y;
// foo("hello") + y;
// foo(x) + y + "hello";
}
_ = bar("hello", 2)
//_ = bar(1, 2)

40. Type checking
foo = 1 + "bar";
“Types int and string are
not compatible”

41. Type inference
function foo(s) {
String.length(s);
}
function bar(x, y) {
foo(x) + y;
}

42. Type inference
int function foo(string s) {
String.length(s);
}
int function bar(string x, int y) {
foo(x) + y;
}

43. Strong static typing without any hassle.

45. A single language

46. Client and server
// Will be on server side:
function db_update(value) {
/mydb/counter <- value
}
// Will be on client-side:
function dom_update(value) {
#counter = value
}

47. Client and server
function update(value) {
/mydb/counter <- value;
#counter = value
}

48. Client and server
function init() {
#counter = /mydb/counter
}

49. Transparent distribution
between client and server

51. Precise control

52. Live Demo

53. // a dangerous function
protected function dangerous() { 42 }
// a bit of code
function code() { dangerous() }
// an innocent bit of client code
client function malicious() { code() }

54. // database operations are protected BY DEFAULT
database mydb {
string /personal_data
}
function code() { /mydb/personal_data }
// Try those different directives:
// protected
// server -> meaning less
// terminal error without «protected» on code
client function malicious(code) { code() }

55. Precise control
client server
exposed protected
sync async
public private

57. Strong database mapping

58. Data declaration
type user = {
string mail, int age,
list(string) comments
}
database dbname @mongo {
user /user[{mail}] // primary key
int /user/age = 18 // default value
}

59. Data queries
/db/col[name == v; order -score; limit 50];
== skip in [e1, e2]
!= limit or
< order and
<= not
>
>=

60. Data queries
/db/col[n > 10 and n < 20];
opa
use db
db.col.find(
{$and : [{ n : { $gt : 10 } },
{ n : { $lt : 20 } } ]
})
mongoDB shell

61. Data updates
/db/path[id == id] <- { n += 1, l <+ e }
n += 800 l pop
n++ l shift
n-- l <+ e
n : v l <++ [e1, e2, e3]

62. Transparent mapping between db and code values.
Type checking included.
(even for mongoDB)

64. Non-blocking

65. function fib(n) {
if (n == 0)
0
else if (n == 1)
1
else
fib(n-1) + fib(n-2)
}

66. mo
/ / D e mo n s t ra te a c li en t d o esn ’ t b l ock an o the r
De de
/ / S e ve r a l c om pu ta ti on at the tim e ar e po s sib le
ive hi
/ / T a lk a b ou t CP S
L o
T i m po r t s t d li b. th em es .b oot s tra p
/ / n a iv e f ib on ac ci
f u nc t io n f ib (i d, n ) {
if (n = = 0 )
0
el s e i f (n = = 1)
1
el s e
f ib ( n - 1) + f ib (n -2 )
}
s e rv e r f u n ct io n ac ti on (_) {
# re s ul t = f ib (4 0)
}
f u nc t io n p ag e( ) {
<d i v c l a ss =" we ll ">
<b u t t on c la ss =" bt n" on c lic k ={a c tio n }>C o mpute</button>
<h 2 i d= #r es ul t cl as s=" w ell " />
</ d iv >
}
S e rv e r. s t a rt (
Se r ve r . h tt p,
{ ~ pa g e , t it le : "H el lo f ibo " }
)

70. opalang.org
@opalang
@henri_opa

71. opa create myapp
make run

72. Windows: bit.ly/O1JiKc
Linux, Mac: sudo easy_install pip && sudo pip install dotcloud
git clone https://github.com/dotcloud/opa-on-dotcloud
dotcloud create myapp
dotcloud push myapp opa-on-dotcloud