zongors-reality-engine/docs/SPECIFICATION.org

• ZRE (Zongors Reality Engine) Design parameters
  • What is zre?
• ZRE Grammar and Specification
  • Types
• Basic Types
  • numeric
  • string
  • binary
  • logical
  • datastructure
    • Array
    • Map
    • Tunnel
    • Basic operators
    • logical / bitwise operators
    • keywords
  • Object
  • Tunnel
    • transtypes for tunnels
  • Functions
  • Control flow
    • loops
    • branching
  • Error handling
  • Localization
  • Libraries and "includes"
  • Testing
    • assertion
  • Measurements

ZRE (Zongors Reality Engine) Design parameters

What is zre?

zre is an domain specific language for 3d games with C/Lua style syntax. The compiler is written in C which should make it easy to port to other systems.

ZRE Grammar and Specification

Types

• there are also a list of "substantial types" which come with the language which are the building blocks for more complex types. If you are coming from object oriented languages you can think of self as "primitive types"
• Note that these look like classes but act like structs the methods actually have a implied struct as their first argument

type «token» {
  init() {
    // values
  }
}

! example
type Vec3 {
  init(x real, y real, z real) {
     this.x = x;
     this.y = z;
     this.y = z;
  }
}

Basic Types

numeric

• real

  • 32 bit floats

• int

  • 32 bit integer

• nat

  • 32 bit unsigned integer (for loop counting and indexing)

string

• str

  • utf8 / ascii encoded string depending on the language output

normal string

"«utf8 encoded characters»"

string interpolation

"«utf8 encoded characters» ${some_var}"

binary

• byte

  • same as uint8 or c char, also used for interop

logical

• bool

  • true / false

datastructure

Array

Array of a specific type

let «variable» = [val1, val2, ...];

Map

Hashmap

let «variable» = {key1: val1, key2: val2, ...};

Tunnel

described in "tunnel" section

Basic operators

The following is a list of global operators and their effect:

• !

  • comment

• ??

  • unwrap or

• .?

  • null check or return error
• • • addition
• • • subtraction
    • negation
• • • multiplication

• /

  • divisor

• ^

  • power

• ==

  • equals

• <

  • less than

• >

  • greater than

• >=

  • greater than or equals

• <=

  • less than or equals

• .

  • accessor

• ++

  • inline add 1

• –

  • inline subtract 1

• +=

  • inline add n

• -=

  • inline subtract n

• *=

  • inline multiply n

• \=

  • inline divide n

logical / bitwise operators

• mod

  • modulo

• not

  • logical not

• and

  • logical and

• or

  • logical or

• xor

  • logical xor

• band

  • bitwise and

• bor

  • bitwise or

• bxor

  • bitwise xor

• srl

  • bit shift right

• sll

  • bit shift left

keywords

let

let operator

let «token» = true;

is

checks if a object is of that type

if («token» is real) {
  print("hello yes self is a real?");
}

also used for letting constants

as

coerces a type as another type if possible

let «token» = 0; ! default is int
some_functon(«token» as real); ! needs a real

in

checks if a object's type, or a type implements a contract

if («token» in Tunnel, Drawable) {
  print("im tunnel-able and draw-able");
}

also used inside of the for loops

for («token» in «collection») { «body» }

Object

An object is an invoked type.

let «variable» = «type»(«fields», …);

Tunnel

Represents a path to a file, url endpoint, other process endpoint (like a socket, etc.)

Tunnels are inspired by translators in gnu/hurd, plan9 9p protocol, and unix sockets

tunnels are invoked like objects, but have scope like control flow end scope closes the tunnel

note the type must always be of a type which is "tunnel-able" i.e. Files, sockets, etc

Tunnels have almost the same interface as 9p since they are closely based on 9p.

transtypes for tunnels

tunnel? : attach(tunnel_object) -> open communication

success? : tunnel_object.clunk() -> close communication

success? : tunnel_object.flush() -> cancels long operation and dumps whatever is in buffer

success? : tunnel_object.open(resource, mode) -> opens a tunnel for doing operations on

success? : tunnel_object.create(resource) -> creates the object from the database graph/file from file structure

data? : tunnel_object.read(resource) -> reads from a tunnel

success? : tunnel_object.write(resource, data) -> writes to a tunnel

success? : tunnel_object.remove(resource) -> removes the object from the database graph/file from file structure

stat_data? : tunnel_object.stat(resource) -> returns the status of the file/resource

version? : tunnel_object.version() -> returns the version code for the connected tunnel

success? : tunnel_object.walk(path_or_endpoint) -> moves around the filesystem or through the graph

! client 
let endpoint = Client("tcp://path/to/source");
let tunnel = endpoint.attach(user, auth);
let data = tunnel.open("/some/resource").read();
std.write(data);
data.flush();
endpoint.clunk();

! server
let server = Server("tcp://0.0.0.0:25565");
s.bind("/some/resource", fn () str {
   return "hello world";
})
server.start();

Functions

Functions are all typechecked statically at compile time. Since we always have a "default type" for all constant values or a developer can use the as keyword we do not have to define all values like in C, while keeping the same type safety as a more strongly typed language.

fn «token» («parameter» «type», ...) «return_type» {
  «body»
}

• Built in transtypes

  • sort
  • filter
  • trig functions
  • calc functions
  • statistical functions

Control flow

loops

for («token» in «collection») { «body» }

iterates through each object in the collection setting it to token

while («boolean expression») { «body» }

loops until the expression is false

do (let «variable» = initial_value, end_value, increment) { «body» }

loops from initial value to end value by increment value (like a for loop in other languages)

branching

if («boolean expression») {

} else if («boolean expression») {

} else {

}

switch (value) {
  case A:
  case B:
  case C:
  default:
}

Error handling

Error handling is much like in C/C++ where a try catch can be used.

let rr = nil;
let var = rr ?? 0; ! value is 0
try {
   let other_var = 1 / rr; ! will panic

} catch (e) {
   print("Caught error ${e}");
}

Localization

will look up the text of «token» in the linked localization.json file

#«token»

{
  "some_token": [
    "localization_1": ""
  ],
  "some_other_token": [
    "localization_1": "",
    "localization_2": ""
  ]
}

Libraries and "includes"

In most languages the include or use statements get libraries which link to other files and so on.

use "./some_local_file.zre"

Testing

assertion

assert(«expression», «expected output») ! returns «error or none»

Measurements

• types

  • time

    • unit

      • seconds (s)

    • subtypes

      • date

        • Default is ISO 8601

  • length

    • unit

      • metre (m)

    • subtypes

      • angle

        • radian (rad)

  • mass

    • unit

      • kilogram (kg)

  • electric current

    • unit

      • ampere (a)

  • temperature

    • unit

      • kelvin (K)

  • amount of substance

    • unit

      • mol (mol)

  • luminous intensity

    • unit

      • candela (candela)