Actor Lang¶
A small language I made to give life to the pseudocode one of my teacher used to teach us actor programming.
The language is pretty small so only basic arithmetic and comparisons can be done (and obviously standard actor programming actions). It only supports integers, booleans, strings and actor references.
Licence¶
This software is released under the MIT licence. See the full licence text.
Language syntax¶
Basic types¶
Integers:
10,-42,+1337Strings:
"Hello, world!"Booleans:
true,false
Maths¶
Basic maths are supported so you can do arithmetic or boolean logic:
1 + 1
b * b - 4 * a * c
(1 + 2) * 3
true || false
true || false && myVar
x % 2 == 0
Conditional execution¶
if (x == y) {
...
}
if (x < y) {
...
} else {
...
}
Loops¶
for (i in 0..10) {
...
}
Iterates in a range from 0 to 10 (inclusive).
You can also iterate on decreasing values:
for (i in 10..0) {
...
}
Iterates in a range from 10 to 0 (inclusive).
You can use «complex» expressions for the range bounds:
for (i in start..(a + b)) {
...
}
Printing data¶
display "hello";
display (1 + 2) * 3;
display true || false && true;
Prints three lines:
hello
9
true
Actor behavior definition¶
An actor behavior definition follows this pattern:
<actor type> (<state var1>, <state varN>) [<message item1>, <message itemN>] = <statements>
A behavior is executed when a message matching a pattern is received by an actor.
Example:
MyActor () [item1] = display item1;
MyActor (State) [item1, item2] = {
display item1;
display item2;
};
Tagged messages¶
To enable calling the right behavior of an actor with multiple behaviors of the same arity, one can tag the messages with literal values in the patterns.
Example:
MyActor () ["display-one"] = display 1;
MyActor () ["display-two"] = display 2;
These behaviors will be executed on receiving a message containing either "display-one" or "display-two".
Changing behavior¶
An actor can change its type (and so its behavior) based on a received message:
Empty () ["set", x] = become Full (x);
Full (X) ["get", sender] = {
send [X] to sender;
become Empty ()
};
Sending messages¶
send [42] to anActor;
send ["hello", 1337] to anotherActor;
Actor self reference¶
In a behavior, the self variable is a reference to the actor executing the code.
Creating actors instances¶
Instantiating an actor from a given type with a given state (e.g. MyActor (42)) is done like so:
myInstantiatedActor = create MyActor (42);
Examples¶
Exemples can be found in the src/dist/examples folder.
Installation¶
To install actorlang you must unpack a distribution from a GitHub release or one you built yourself.
From source¶
First you need to build from source if not done yet: Building from source.
Then unpack a distribution outputted in
<repo>/build/distributions/.
Executing code¶
To execute code you must run the actorlang script with an Actor Lang file as an argument.
Example:
./actorlang ./examples/counter.actor