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The length of the spec isn't really relevant is it? Or are you implying that C is about as complex as Java?

pcwalton 9y ago
C is significantly more complex than Java. The memory model of Java is simple (multithreading notwithstanding), because it's memory-safe and garbage collected. Not so for C, which has very subtle rules, which result in undefined behavior if broken.
- boomlinde 9y ago
  The question here isn't whether it's easier to write correct C programs than Java programs, it's whether C is a simple language. Subtle UB, as much of a headache as it can be to a programmer using the language, in this case leads to simpler implementation of a compiler.
  - kevinmgranger 9y ago
    I think you've pointed out the distinction many miss when talking about simplicity, which results in talking past each other: simplicity for the user and simplicity for the compiler writer are totally different things. Java is simpler for the user but more complex for the implementer, and C is more complex for the user but simpler for the implementer.
  - pcwalton 9y ago
    No, it doesn't. Maybe it did in 1978, but modern C compilers have to go to heroic lengths to do things like alias analysis that would be easier if the aliasing rules of C weren't so subtle. In Java the question of "can pointer A alias pointer B" is simple (unless typeof A derives typeof B or vice versa, the answer is no). In C, due to TBAA, it's hideously complex.
    - jcranmer 9y ago
      If you look at software engineering and static analysis papers for a language like Java, there's often a discussion about using stuff like 2-object, 3-call site context sensitive alias analyses built on more or less fairly standardized Datalog rules. If you look at C or C++, the response is generally "you want a precise alias analysis? fall down in riotous laughter". The rules for TBAA are complex, and many C/C++ programs violate those rules because it's so hard to actually make sure you're not violating them, and half of the purpose of using C/C++ is actually to be able to do the kind of type-punning that TBAA prohibits.
    - boomlinde 9y ago
      I mean writing a compiler that fulfills the specification. Whether a design complicates the implementation of alias analysis doesn't really change whether it is simple.
- akvadrako 9y ago
  The rules for java memory management could probably fill 200 pages just by itself and it's not easy to debug issues with leaks, excessive overhead and the several layers and variants of garbage collectors. C's memory model is trivial by comparison.

C is significantly more complex than Java. The memory model of Java is simple (multithreading notwithstanding), because it's memory-safe and garbage collected. Not so for C, which has very subtle rules, which result in undefined behavior if broken.

boomlinde 9y ago
The question here isn't whether it's easier to write correct C programs than Java programs, it's whether C is a simple language. Subtle UB, as much of a headache as it can be to a programmer using the language, in this case leads to simpler implementation of a compiler.
- kevinmgranger 9y ago
  I think you've pointed out the distinction many miss when talking about simplicity, which results in talking past each other: simplicity for the user and simplicity for the compiler writer are totally different things. Java is simpler for the user but more complex for the implementer, and C is more complex for the user but simpler for the implementer.
- pcwalton 9y ago
  No, it doesn't. Maybe it did in 1978, but modern C compilers have to go to heroic lengths to do things like alias analysis that would be easier if the aliasing rules of C weren't so subtle. In Java the question of "can pointer A alias pointer B" is simple (unless typeof A derives typeof B or vice versa, the answer is no). In C, due to TBAA, it's hideously complex.
  - jcranmer 9y ago
    If you look at software engineering and static analysis papers for a language like Java, there's often a discussion about using stuff like 2-object, 3-call site context sensitive alias analyses built on more or less fairly standardized Datalog rules. If you look at C or C++, the response is generally "you want a precise alias analysis? fall down in riotous laughter". The rules for TBAA are complex, and many C/C++ programs violate those rules because it's so hard to actually make sure you're not violating them, and half of the purpose of using C/C++ is actually to be able to do the kind of type-punning that TBAA prohibits.
  - boomlinde 9y ago
    I mean writing a compiler that fulfills the specification. Whether a design complicates the implementation of alias analysis doesn't really change whether it is simple.
akvadrako 9y ago
The rules for java memory management could probably fill 200 pages just by itself and it's not easy to debug issues with leaks, excessive overhead and the several layers and variants of garbage collectors. C's memory model is trivial by comparison.