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9111 :: Compiler ignores my `if` a throws an error

• archnim (orginal) [2022-04-17T12:11:13+02:00] view original

  Hello world. Here is my code:

  proc myProc[T](i: T):T =
    if i is SomeNumber:
      return i * 2
    else:
      return i
  
  
  myProc true
  Run

  Compiler considers that I multiply a bool by an int. It says: Error: type mismatch: got <bool, int literal(2)>

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• aEverr (orginal) [2022-04-17T12:21:02+02:00] view original

  The type of I and the return type MUST be known on compile time.

  Nonetheless, this can be fixed by replacing the if with a when (converting the run time check into a compile time check)

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• archnim (orginal) [2022-04-17T12:26:43+02:00] view original

  I thought there were a workaround. Thank you very much.

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• mardiyah (orginal) [2022-04-18T02:26:44+02:00] view original

  there's just make up an overloaded * function ie. proc

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• ynfle (orginal) [2022-04-18T03:15:47+02:00] view original

  Use when to test the type, not if

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• PMunch (orginal) [2022-04-19T10:05:43+02:00] view original

  Just creating an overload for * is probably a bad idea. Actually checking the type on compile-time with when is definitely the better option in this case as the type is always known on compile-time.

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