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4.9.1 Language versioning

Because the coNCePTuaL language is still under development, the programmer is forewarned that major changes are likely. Changes may prevent old code from compiling or, even worse, may cause old code to produce incorrect results (e.g., if scoping or block structuring are altered). To mitigate future language changes coNCePTuaL enables programs to specify which version of the language they were written to. The syntax is straightforward:

<version_decl> ::= REQUIRE LANGUAGE VERSION <string>

The parser issues a warning message if <string> does not exactly match the language version supported by the compiler. If the program successfully compiles after a version-mismatch warning, the programmer should check the output very carefully to ensure that the program behaved as expected.

The current version of the coNCePTuaL language is ‘1.5’. Note that the language version does not necessarily correspond to the version of the coNCePTuaL toolset (see Usage) as a whole.

Scott Pakin,