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58 lines
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.. @raise litre.TestsAreMissing
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.. _FAQ:
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Frequently Asked Questions about Swift
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======================================
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Obviously many more questions can be added.
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Do you plan to rewrite the Swift compiler in Swift?
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---------------------------------------------------
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Not in the short term. C++ is a very pragmatic language for implementing
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compilers, since it has good performance characteristics and allows higher-level
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programming idioms than C.
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That said, we do expect Swift to a better language than C++ in a number of ways,
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so why don't we implement the compiler itself in Swift? There are a couple of
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reasons that bootstrapping is not a good idea, at least in the short term:
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* This complicates bringup of the compiler, because you have to move both the
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compiled language and the compiler at the same time as the language evolves.
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* We want the language evolution and direction to be driven by general purpose
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programming challenges, not by the specific needs of compiler hackers. The
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urge to "scratch our own itch" might be too great.
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That said, we are writing the runtime library in Swift itself. We may also
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decide to rewrite the compiler in Swift sometime in the distant future when the
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language settles down. At that point, it may be a good opportunity to revisit
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previous (internal to the compiler) design decisions, and we do expect and hope
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Swift to be a great language for doing many things, including implementing
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compilers.
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Won't the design and evolution of Swift be warped by being too C++-centric?
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---------------------------------------------------------------------------
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This is a common question from Objective-C programmers, primarily those who
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really dislike C++. There are a lot of reasons you can have hope that Swift
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will end up being a great "successor to Objective-C instead of a "C++
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replacement":
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* The compiler team has expert-level knowledge of Objective-C (the language),
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having implemented the compiler for it from the ground-up. We probably know
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its dark corners better than anyone.
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* The Swift team has broad experience with a number of other programming
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languages, including C/C++/Objective-C, Python, Haskell, Java, Javascript,
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C#, ...
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* We know C++ well enough to not want to repeat its mistakes.
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It turns out that there are a lot of reasons to dislike C++, and those people
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who spend a lot of time writing C++ code are some of the most expert people at
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explaining its varied faults. Don't consider use of C++ to be the same as
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"love" for it. :)
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