Lexical ScopeΒΆ

A lexical scope is a region of the source code in which a set of referable identifiers are made available.

First, all members of a structural value are made available to each other. For instance, in the following snippet:

    x = y
    y = 'value'

the value of x is the 'value' string because y is defined in the same structural value as x, and is therefore in the same scope as x.

The members of a structural value are also made available to its nested structural values. In other words, identifiers that are at a lower level can be accessed in structural values that are at a higher level. This allows the following value to be completely legal:

    v = 'value'
    x = {
        a = v

Next, all type members of a type are also made available to each other. This is generally used to specify a type relationship between generic members, and to ascribe contract members with the identifier of a locally defined generic member. For instance, the following snippet:

    T <: Any
    some: T
    else: T

represents a type that accepts only values which contain some and else concrete members with a common subtype T.


Moving nested structural values to a lower level in the source code is likely to reduce the amount of identifiers that exist simultaneously in the context, therefore reducing code complexity.