Primitive Values

    UCG has a few primitive types.


    Boolean types can be either true or false. They are represented by symbols of the same name.



    An Integer is any 64 bit integer number.



    A Float is any 64 bit floating point number. You indicate a number is a Float by including a decimal point. Any number with a decimal point is a float.



    Strings are any double quoted text. You can use the \ to esacpe characters in the text.

    "This is a string";
    "This is an escaped \"string\"";

    NULL or the Empty type

    NULL is the empty type. It represents the absence of a value. It is represented by the symbol NULL. The empty type is special in that any field regardless of type can be assigned the NULL value and any field of NULL value can be assigned any type. This is most useful when you need a module, tuple, or function to have fields or parameters that can be any type.

    let empty = NULL;

    Complex types

    UCG also has two complex types.


    Tuples are an ordered set of name value pairs. They are delimited by braces and should contain 1 or more name = expression pairs separated by commas. Trailing commas are allowed. Field names can be barewords with no spaces or they can be quoted strings.

    let tuple = {
        field = "value",
        inner = {
            number = 1,
        "quoted field" = "quotd value",


    Lists are a 0 indexed heterogenous list of expressions. The are delimited by square brackets and should contain 1 or more expressions separated by commas. Trailing commas are allowed.

    let list = [1, "two", {three = 3},];

    Next: Expressions