Policy definition DSL translator (LacLang)

DO NOT USE IN PRODUCTION.
This implementation is in early development. It has not been reviewed or audited. It is not suitable to be used in production. Expect bugs!

The DSL is used to define policy structure and translate it to intermediate representation, that will further be translated into actual policy configuration for onchain initialization. The DSL is high-level markup language without expressions, with imports, declarations and compiler directives. The syntax is simple yet versatile, so anyone can combine artifacts into policies almost intuitively.

Data types

There are 5 data types, which are mapped 1 to 1 with solidity data types. The bytes can hold any encoded type as a workaround for absent types (like arrays).

bool := true | false (↦ bool)

string := "any string" (↦ string)

bytes := 'bytes with 0x prefix' (↦ bytes)

address := address with 0x prefix (↦ address)

number := any unsigned decimal number fitting uint256 (↦ uint256)

Declarations

Values can be declared as constans and variables. Constants must be initialized right away.

constant - declares constant

constant bytes = '0xdeadbeef';

  var - declares variable (variables must not be initialized!) (var address proxyAddress;) Variables can be injected - meaning their value is meant to be replaced with the value of a corresponding attribute on some kind of an interceptor (e.g. backend). Then the inject("<name_of_the_attribute>") syntax must be used.

var inject("IS_PRODUCTION") bool mutateState;

  artifact - declares artifact via its address literal (no reference yet)

artifact dayOrNight = 0x95222290DD7278Aa3Ddd389Cc1E1d165CC4BAfe5

  instance <return type> * of <artifact> takes ([<constants, vars, instances>]) /*OPTIONAL:*/ with ([<constants>]); - declares instance, that implements artifact (can be literal or artifact reference), that consumes takes... in exec and with... in init. If no with clause used, the instance considered stateless (init method will not be dispatched).

instance bytes codedImage of imageCoder takes (imageInBmp, resolutionInstanceOutput) with (codec);

Statements:

import <path> - prepends .lac code found under <path> to the current source file. Must be used in the very beginning of the file if used at all.

  pragma <directive> - compiler directive. Used right after import statement. Available directives:

• injected-only Forces the compiler to allow only injected variables.

  evaluate <instance name that returns bool> - defines the root of the policy = boolean! instance that will return as a policy evaluation result evaluate finalInstance;

  All constuctions end with semicolon ;
Pay allention to quotes
Only boolean artifact can be evaluated
Only single string comments using //

Valid example:

import "./header.lac";
import "./lib.lac";

pragma injected-only;

var inject("is_dev") bool boolVar;
// var bytes spare;

constant number init1 = 0;

artifact art2 = 0xB60B02062d1256A79C81A061a9277e84ffbB0Ff7; // random

instance number inst1 of art1 takes (num1, str1, "here I am") with (init1, bts1, bool1);
instance bool statefulInstance of art2 takes (inst1, addr1, boolVar, bts1, inst1, bool1) with ();
instance string inst3 of art2 takes (inst1, statefulInstance) with ("initialize me", '0xd00d', 0xB60B02062d1256A79C81A061a9277e84ffbB0Ff7);
instance bool statelessInstance of 0x4838B106FCe9647Bdf1E7877BF73cE8B0BAD5f97 takes (inst3);

evaluate statelessInstance;