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1140 :: var qualifier optional in variable declaration

• kuba (orginal) [2015-04-18T09:17:02+02:00] view original

  I'm aware bringing yet another syntax topic will be bashed instantly. I'm sorry I can't resist.

  Don't you think having a 'var' in front of every declaration introduces quite a bit of noise and is hard to read? I can obviously see a purpose for var to mark mutability of a variable, but since we also have 'let' isn't it redundant? If not what is reasoning behind it, perhaps I'm missing important point?

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• Varriount (orginal) [2015-04-18T10:14:59+02:00] view original

  'let' is for immutable declaration, 'var' is for mutable declaration. Besides, who says you have to put 'var' in front of every variable declaration?

  This:

  var
    a: string
    b = 5
  Run

  Is perfectly legal syntax.

  And before you ask, doing without 'var' and 'let' altogether would be ill advised - such a change would cause ambiguities to arise between variable declaration and assignment.

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• kuba (orginal) [2015-04-18T10:55:20+02:00] view original

  Nice, I didn't you can group variables - looks much better. Thanks.

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• gokr (orginal) [2015-04-19T11:55:23+02:00] view original

  @kuba: I don't want to sound rude, but haven't you read tutorial 1? http://nim-lang.org/tut1.html#the-var-statement

  I am all for asking questions and getting answers - but I would hope beginners (like myself a few months back) at least reads the two tutorials first.

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• kuba (orginal) [2015-04-19T16:47:25+02:00] view original

  ok, I will reread it before bringing next question.

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• repax (orginal) [2015-04-22T11:32:09+02:00] view original

  Requiring var is an important feature for correctness that eliminates a whole class of bugs stemming from accidental variable declarations in typos:

  var variable = default()
  ...
  varaible = foo() # notice the typo
  ...
  useValue(variable)
  Run

  This class of bugs is a huge problem in languages with implicit variable declarations.

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• def (orginal) [2015-04-22T11:50:26+02:00] view original

  You can easily get Go's := with a template if you really don't like the look of var:

  template `:=`(x, y) =
    var x = y
  
  x := 10
  echo x
  Run

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• Sixte (orginal) [2015-04-22T19:38:17+02:00] view original

  I changed the 'var' to 'let' ... When I already have an assignment, the prob. that the value remains unchanged is very high. It could make sense to declare a let value at top of the scope and to assign a value later,e.g. deep in the scope , only once of course. The value could be used according with the scope where the value was declared. But Nim doesn't support such a "deep instantiation". However, it would theoretically (with some effort) be possible to infer the type even with/in late assignment.

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