Root names

These names are bound directly in the global scope.

TRUE, FALSE

TRUE -> Bool
FALSE -> Bool

The two boolean values. They are also available as bool.TRUE and bool.FALSE.

TRUE & FALSE         # => FALSE

type

type value -> Text

Returns the name of the type of value: "Bool", "Numb", "Text", "List", "Namespace", "Func", "Promise" or "Undefined".

Like other functions, type is applied to each item of a tuple, so it never returns "Tuple" or "Nothing": type (1, "a") is ("Numb", "Text"), and type () is ().

type 42              # => "Numb"
type [1, 2]          # => "List"
type text.size       # => "Func"
type (1, "a")        # => ("Numb", "Text")

parse

parse source -> Func

Compiles the Swan expression in the text source and returns a function. The function takes a namespace and evaluates the expression inside it, so the expression can use the members of the namespace, and the names visible where the namespace was created.

The source is parsed once, when parse is called. A syntax error does not make parse fail: the function returns Undefined when it runs. A source that is not text gives Undefined, and so does applying the function to something other than a namespace.

area = parse "width * height"
area {width: 3, height: 4}     # => 12
area 42                        # => Undefined

bind

bind name value -> Nothing

Binds name to value in the global scope, wherever it is called from, and returns Nothing. name is a text, or a tuple of texts to bind several names at once, following the rules of destructuring.

bind is how a function, or a callback waiting on a promise, makes a value available to the rest of the program. In a template, the global scope is the engine's global scope, shared by every document the engine renders.

f = () -> bind "seen" TRUE
f()
seen                           # => TRUE
bind ("a", "b") (1, 2)
a + b                          # => 3

label

label name value -> value

Like bind, but returns value instead of Nothing, the way : differs from =.

label "answer" 42              # => 42
answer                         # => 42