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Type parameterization has been around for a long time, but all existing implementations make tradeoffs the Go team is not willing to make: http://research.swtch

Type parameterization has been around for a long time, but all existing implementations make tradeoffs the Go team is not willing to make: http://research.swtch.com/generic http://research.swtch.com/generic

pjmlp 12y ago
Or don't know how to implement. It has been pointed out multiple times that the page you refer to, only focus on C++ and Java, while forgeting about all the other languages.
- crawshaw 12y ago
  If there exists an implementation of type parameterization that imposes neither a compile time cost nor a run time cost, I would be interested in reading about it. The languages and compilers I'm familiar with (Scala, Haskell, MLton) all pay a cost, usually in compile time.
  - kvb 12y ago
    What's problematic about .NET's approach[1]? [1] http://research.microsoft.com/en-us/um/people/akenn/generics/FOOL2003.ppt http://research.microsoft.com/en-us/um/people/akenn/generics...
    - MichaelGG 12y ago
      The answer, as I understand, is that .NET has to copy code for each non-reference-type instantiation. .NET gets away with it because most types are reference typed and can use the same code. In F#, you can use hat types via inlining to get even more power. Like creating a map function that works directly on List, Array, and Set - but without using any common interface. Pretty neat, but it emits the function's IL into every callsite so it can get out of hand. I recall there being a mailing list thread on Go where the designers addressed this. I've no idea how Go is implemented so perhaps the multiple-copies problem is actually significant.
      - kvb 12y ago
        Technically, I believe that value types with the same layout could share implementations (though I don't believe this is implemented). In any case, if you don't have generics you have to do the same thing by hand anyway (e.g. create an IntList type, a DoubleList type, etc.), so I can't see how that's any better. More likely, I think, is that Go doesn't do JIT compilation, so there would be some challenges getting a comparable implementation built on Go's runtime. But .NET's new native toolchain solves the same problem, so it's clearly not insurmountable.
      - pjmlp 12y ago
        In cases static linking is used, which happens to be Go's case, this can be done at link time. Also addressed by Ada generics for example. There are many others. Strong typed languages with generics go back to CLU (1974), so there are lots of research material, as well as, real languages if one steps outside Java/C++ implementation mindset.
- warfangle 12y ago
  I'm uh, pretty sure the people who practically invented Unix know how to implement generics if they wanted to.
  - pjmlp 12y ago
    Sometimes people are placed in pedestals, but they are only human.
    - NateDad 12y ago
      They are human. They've also been programming for over 30 years with numerous big successes that prove they know what they're doing.
      - pjmlp 12y ago
        So how successful would have been UNIX and C if AT&T reacted sooner than it did in terms of ownership and prevented universities access to them? Edit: Removed stupid comment.

pjmlp 12y ago

Or don't know how to implement. It has been pointed out multiple times that the page you refer to, only focus on C++ and Java, while forgeting about all the other languages.

crawshaw 12y ago
If there exists an implementation of type parameterization that imposes neither a compile time cost nor a run time cost, I would be interested in reading about it. The languages and compilers I'm familiar with (Scala, Haskell, MLton) all pay a cost, usually in compile time.
- kvb 12y ago
  What's problematic about .NET's approach[1]? [1] http://research.microsoft.com/en-us/um/people/akenn/generics/FOOL2003.ppt http://research.microsoft.com/en-us/um/people/akenn/generics...
  - MichaelGG 12y ago
    The answer, as I understand, is that .NET has to copy code for each non-reference-type instantiation. .NET gets away with it because most types are reference typed and can use the same code. In F#, you can use hat types via inlining to get even more power. Like creating a map function that works directly on List, Array, and Set - but without using any common interface. Pretty neat, but it emits the function's IL into every callsite so it can get out of hand. I recall there being a mailing list thread on Go where the designers addressed this. I've no idea how Go is implemented so perhaps the multiple-copies problem is actually significant.
    - kvb 12y ago
      Technically, I believe that value types with the same layout could share implementations (though I don't believe this is implemented). In any case, if you don't have generics you have to do the same thing by hand anyway (e.g. create an IntList type, a DoubleList type, etc.), so I can't see how that's any better. More likely, I think, is that Go doesn't do JIT compilation, so there would be some challenges getting a comparable implementation built on Go's runtime. But .NET's new native toolchain solves the same problem, so it's clearly not insurmountable.
    - pjmlp 12y ago
      In cases static linking is used, which happens to be Go's case, this can be done at link time. Also addressed by Ada generics for example. There are many others. Strong typed languages with generics go back to CLU (1974), so there are lots of research material, as well as, real languages if one steps outside Java/C++ implementation mindset.
warfangle 12y ago
I'm uh, pretty sure the people who practically invented Unix know how to implement generics if they wanted to.
- pjmlp 12y ago
  Sometimes people are placed in pedestals, but they are only human.
  - NateDad 12y ago
    They are human. They've also been programming for over 30 years with numerous big successes that prove they know what they're doing.
    - pjmlp 12y ago
      So how successful would have been UNIX and C if AT&T reacted sooner than it did in terms of ownership and prevented universities access to them? Edit: Removed stupid comment.