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9 Library Concepts

Specifications may be  named by  definitions and collected in  libraries. In the context of a library, the (re)use of a specification may be replaced by a  reference to it through its name. The current association between names and the specifications that they reference is called the  global environment; it may vary throughout a library, e.g., with  linear visibility the global environment for a named specification is determined exclusively by the definitions that precede it.

With  referential transparency, a reference to a named specification may always be replaced by a copy of the specification itself. Thus in principle, all references to names could be eliminated from the specifications in a library--provided that there are no mutual or cyclic chains of references, i.e., the library can be linearized.

The local environment given to each named specification in a library should be independent of the other specifications in the library. This allows the well-formedness of each named specification to be independent of the references made to it.

[DTS] I don't understand the last sentence.
Discharged: Delete it.
A library may be located at a particular  site on the Internet, and addressed by a  URL (uniform resource locator). Each library may incorporate the  downloading of named specifications from other libraries, which takes place whenever the library is used.

The semantics of a specification library is a map taking each specification name defined in it to the semantics of that specification. The initial global environment for the library is determined by the semantics of any downloaded specifications.


CoFI Note: S-1 --Version 1.3-- 25 April 1997.
Comments to cofi-semantics@brics.dk

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