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Comment by djur | Hacker News Reader

But a colon is also often used to indicate a mapping of names or categories to value. For instance:

  Breakfast: eggs and bacon
  Lunch: falafel sandwich
  Dinner: BBQ pork and slaw

The type of the variable is the "explanation" here.

  val x: String

"x, which is a String"

  val x: String = "hello"

"x, which is a String, is initialized with 'hello'"

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Your examples have the things on the right and the type on the left, and then used it to describe why examples on the left and [types] on the right makes sense...

If anything you've just argued that

String: x, y

is a preferable declaration style.

The point of the list isn't to say "eggs and bacon is a kind of breakfast", it's to say "breakfast is eggs and bacon". It's "name: details about name", not "type: instance".

Wouldn’t that argue in favor of

  val breakfast: “eggs and bacon” = String

and not

  val breakfast: String = “eggs and bacon”

My intention was solely to counter the idea that using ":" to mean "is" or "is a" is somehow inconsistent with written English. I don't think it's always necessary or even desirable to match the use of symbols in programming with English orthography, in any case.

The use of a declaration with initialization as the example here muddies the water. Whatever syntax you use has to work for uninitialized declaration of variables, function arguments, and structure members:

  val breakfast: String
  fun serveBreakfast(breakfast: String)
  struct MealPlan {
    breakfast: String
  }

Declaration with initialization just needs to be consistent with these.

What's the point of the 'val' keyword? It reminds me of Visual Basic's "Dim x As String".

val is immutable, var is mutable

Immutable, as opposed to var which declares a mutable variable.

Having a keyword for variable initialization makes parsing easier and less ambiguous. "let", "var", etc. are also used for this purpose, but I was going along with the example.

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