Talk about ends, rather than means, in macro tutorial introduction.

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Paul Stansifer 2012-10-20 21:54:25 -04:00
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# Introduction
Functions are the primary tool that programmers can use to build
abstractions. Sometimes, though, programmers want to abstract over
compile-time, syntactic structures rather than runtime values. For example,
the following two code fragments both pattern-match on their input and return
early in one case, doing nothing otherwise:
Functions are the primary tool that programmers can use to build abstractions.
Sometimes, however, programmers want to perform abstractions over things that are not
runtime values. Macros provide a syntactic abstraction. For an example of how this
can be useful, consider the following two code fragments, which both pattern-match
on their input and return early in one case, and do nothing otherwise:
~~~~
# enum t { special_a(uint), special_b(uint) };