Basic Types

Numbers

In GreyCat we have int and float to represent numbers, they are both stored as 64bits values under-the-hood.

fn main() {
  var i = 42;     // an integer number known as 'int' in GreyCat (64-bits)
  var pi = 3.14;  // a floating-point number known as 'float' in GreyCat (64-bits)
  var c = 3f;     // a floating-point number, with explicit 'f' suffix
  var x = float::max; // get the highest floating point
  var y = 1e7     // scientific notation
  var z = 1_000_000 // underscore for more readable numbers
}

When using equality check (==) with floats, we use Strict floating point comparison, keep this in mind when handling float point numbers, if needed use Assert::equalsd that takes an epsilon for less stricy comparison.

Booleans

Booleans are specified with bool.

var isTrue = true;
var isFalse = false;

You also have your classical logical operators on booleans.

• && OR
• || AND
• ! NOT

println(isTrue && isFalse); // false
println(isTrue || isFalse); // true
println(!isFalse); // true

Characters

The char type is defined with singlequote ’

var myChar = 'a';

String

The String type is not considered a primitive type in GreyCat, you will remark that all primitives start with a lowercase where as objects start with an uppercase.

fn main() {
  var name = "Luxembourg";
  var sentence = "My city is named: ${name}";
  println(sentence); // My city is named: Luxembourg
}

String templates

For convenience, GreyCat natively offers a template mechanism ${ } , any GreyCat expression can be interpreted in this template.

fn main() {
    var name = "Luxembourg";
    var sentence = "${name} has ${name.size()} characters count in it";
    println("${sentence}"); // Luxembourg has 10 characters count in it
}

String Dictionary

All string literals in GreyCat (who do not use the template syntax, meaning no ${}) are put into a dictionary and mapped to an int internally when compiled.

Every time you access that string it will not allocate additional space, and every equality checks become more performant.

var val = "My String" // This is an optimized string literal
var val2 = "My Second String ${val}" // This is not

Geographic data

GreyCat stores values of type geo in an efficient way: 64-bits for both latitude and longitude.

fn main() {
    var position = geo { 49.6116, 6.1319 };
    println(position);
    println(position.lat());
    println(position.lng());
}

We also offer some aditonal types to handle shapes made of geo points:

• GeoCircle
• GeoBox
• GeoPoly

All three types offer a contains(point:geo):bool function which expect a geoas input and return a bool to indicate if the given point is contained within the area defined by the shape.

GeoCirlcleis defined by a center geoand a floatradius (degrees).

GeoBoxis defined by a south-west and north-east corner geo.

GeoPoly is defined by an array of geo points that outline the polygon.

Both GeoPolyand GeoCircle offer function to retrieve the south-west (sw():geo) and north-east (ne():geo) point of the bounding box containing the shape.