|
unit-interface |
::= |
{ specification [;;] } |
|
unit-implementation |
::= |
{ definition [;;] } |
Compilation units bridge the module system and the separate
compilation system. A compilation unit is composed of two parts: an
interface and an implementation. The interface contains a sequence of
specifications, just as the inside of a sig ... end
signature expression. The implementation contains a sequence of
definitions, just as the inside of a struct ... end module
expression. A compilation unit also has a name unit-name, derived
from the names of the files containing the interface and the
implementation (see chapter 8 for more details). A
compilation unit behaves roughly as the module definition
module unit-name : sig unit-interface end =
struct unit-implementation end
A compilation unit can refer to other compilation units by their
names, as if they were regular modules. For instance, if U is a
compilation unit that defines a type t, other compilation units can
refer to that type under the name U.t; they can also refer to U as
a whole structure. Except for names of other compilation units, a unit
interface or unit implementation must not have any other free variables.
In other terms, the type-checking and compilation of an interface or
implementation proceeds in the initial environment
name1 : sig interface1 end ...
namen : sig interfacen end
where name1 ... namen are the names of the other
compilation units available in the search path (see
chapter 8 for more details) and interface1 ...
interfacen are their respective interfaces.