Druid programming language
Druid is a reactive programming language. Now this is only a prototype to express the idea.
In most traditional programming language, there is assignment.
a = 1;
b = 2;
c = a + b;
But all of them are one-time assignment, which means after executing this assignment, the value of the assignment target(left side) will not change until a next assignment of it comes.
a = 1;
b = 2;
c = a + b; //c is 3
a = 3; //c is 3
b = 4; //c is 3
This Druid programming language is trying to support a new kind of assignment called Reactive Assignment, which, the value of the assignment target will change if any value of the assignment source(right side) changed. This means:
a = 1;
b = 2;
c <- a + b; //c is 3, NOTICE we use the reactive assignment '<-'
a = 3; //c is 5 now!
b = 4; //hey! c is 7 now!
OK, you think the above is not that cool?
a = [1, 2, 3];
b = [4, 5, 6];
c <- a + b; //we can join arrays on change
print(c); //[1,2,3,4,5,6]
a = [7, 8, 9];
print(c); //[7,8,9,4,5,6]
a = [1, 2, 3];
b <- reverse(a); //we can apply functions
print(b); //[3,2,1]
a = [4, 5, 6];
print(b); //[6,5,4]
This brings native support of Reactive Programming into the language level.
Signal is a value binding to an external event, such as file changing, socket arriving, mouse/keyborad event.
It has the syntax @[signalType](arg1, arg2, ...)
With Reactive Assignment, we can do the magic.
a <- @file('a.txt'); //a file signal listening on the file 'a.txt'
once the file a.txt is changed on the disk, for example by using echo "new" > a.txt in the shell command, the value of a will be updated to 'new' automatically.
With the combination of Reactive Assignment, this can bring us magic!
Make sure you have Git, jdk8 and maven installed.
$ curl https://raw.githubusercontent.com/liuyang1204/druid/master/install.sh | bashAfter installation, type:
$ druidto get hint. Typically:
$ druid run file.druidYou can check the test cases for syntax example.