Global names are used to denote value variables, value constructors (constant or non-constant), type constructors, and record labels. Internally, a global name consists of two parts: the name of the defining module (the module name), and the name of the global inside that module (the local name). The two parts of the name must be valid identifiers. Externally, global names have the following syntax:
global-name: ident | ident
The form ident
__ ident is called a qualified name. The first
identifier is the module name, the second identifier is the local
name. The form ident is called an unqualified name. The identifier
is the local name; the module name is omitted. The compiler infers
this module name following the completion rules given below, therefore
transforming the unqualified name into a full global name.
To complete an unqualified identifier, the compiler checks a list of modules, the opened modules, to see if they define a global with the same local name as the unqualified identifier. When one is found, the identifier is completed into the full name of that global. That is, the compiler takes as module name the name of an opened module that defines a global with the same local name as the unqualified identifier. If several modules satisfy this condition, the one that comes first in the list of opened modules is selected.
The list of opened modules always includes the module currently being compiled (checked first). (In the case of a toplevel-based implementation, this is the module where all toplevel definitions are entered.) It also includes a number of standard library modules that provide the initial environment (checked last). In addition, the #open and #close directives can be used to add or remove modules from that list. The modules added with #open are checked after the module currently being compiled, but before the initial standard library modules.
variable: global-name |
<=.cconstr: global-name |
()ncconstr: global-name |
::typeconstr: global-name label: global-name
Depending on the context, global names can stand for global variables
(variable), constant value constructors (cconstr), non-constant
value constructors (ncconst), type constructors (typeconstr),
or record labels (label). For variables and value constructors,
special names built with
prefix and an operator name are
recognized. The tokens
() are also recognized as
built-in constant constructors (the empty list and the unit value).
The syntax of the language restricts labels and type constructors to appear in certain positions, where no other kind of global names are accepted. Hence labels and type constructors have their own name spaces. Value constructors and value variables live in the same name space: a global name in value position is interpreted as a value constructor if it appears in the scope of a type declaration defining that constructor; otherwise, the global name is taken to be a value variable. For value constructors, the type declaration determines whether a constructor is constant or not.