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by layer87 hours ago |
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upvoteby sestep7 hours ago|
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This is an issue in Python but less so in languages like JavaScript that support "field name punning", where you pass named arguments via lightweight record construction syntax, and you don't need to duplicate a field name if it's the same as the local variable name you're using for that field's value.
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upvoteby layer87 hours ago|
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That forces you to name the variable identically to the parameter. For example, you may want to call your variable `loggedInUser` when the fact that the user is logged in is important for the code’s logic, but then you can’t pass it as-is for a field that is only called `user`. Having to name the parameter leads to routinely having to write `foo: blaFoo` because just `blaFoo` wouldn’t match, or else to drop the informative `bla`. That’s part of the tension I was referring to.
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upvoteby twic6 hours ago|
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OCaml has a neat little feature where it elides the parameter and variable name if they're the same:

  let warn_user ~message = ... (* the ~ makes this a named parameter *)

  let error = "fatal error!!" in
  warn_user ~message:error; (* different names, have to specify both *)

  let message = "fatal error!!" in
  warn_user ~message; (* same names, elided *)
The elision doesn't always kick in, because sometimes you want the variable to have a different name, but in practice it kicks in a lot, and makes a real difference. In a way, cases when it doesn't kick in are also telling you something, because you're crossing some sort of context boundary where some value is called different things on either side.
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