ecal

ECAL

ECAL is an ECA (Event Condition Action) language for concurrent event processing. ECAL can define event-based systems using rules which are triggered by events. ECAL is intended to be embedded into other software to provide an easy to use scripting language which can react to external events.

Features

• Simple intuitive syntax
• Minimalistic base language
• Language can be easily extended either by auto generating bridge adapters to Go functions or by adding custom function into the stdlib
• External events can be easily pushed into the interpreter and scripts written in ECAL can react to the events.
• Simple but powerful concurrent event-based processing supporting priorities and scoping for control flow.
• Handling event rules can match on event state and rules can suppress each other.

Getting started

Clone the repository and build the ECAL executable with a simple make command. You need Go 1.14 or higher.

Run ./ecal to start an interactive session. You can now write simple one line statements and evaluate them:

>>>a:=2;b:=a*4;a+b
10
>>>"Result is {{a+b}}"
Result is 10

Close the interpreter by pressing +d and change into the directory examples/fib. There are 2 ECAL files in here:

lib.ecal

# Library for fib

/*
fib calculates the fibonacci series using recursion.
*/
func fib(n) {
    if (n <= 1) {
        return n
    }
    return fib(n-1) + fib(n-2)
}

fib.ecal

import "lib.ecal" as lib

for a in range(2, 20, 2) {
  log("fib({{a}}) = ", lib.fib(a))
}

Run the ECAL program with: sh run.sh. The output should be like:

$ sh run.sh
2000/01/01 12:12:01 fib(2) = 1
2000/01/01 12:12:01 fib(4) = 3
2000/01/01 12:12:01 fib(6) = 8
2000/01/01 12:12:01 fib(8) = 21
2000/01/01 12:12:01 fib(10) = 55
2000/01/01 12:12:01 fib(12) = 144
2000/01/01 12:12:02 fib(14) = 377
2000/01/01 12:12:02 fib(16) = 987
2000/01/01 12:12:02 fib(18) = 2584
2000/01/01 12:12:02 fib(20) = 6765

Further Reading:

• ECA Language
• ECA Engine

License

ECAL source code is available under the MIT License.