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5376 :: How to create new operator ?

• kcvinu (orginal) [2019-10-20T14:47:39+02:00] view original

  Hi all, I would like to know how can i change the iterating operator in this code. This code snippet is from "Nim by Example"

  # Give it a different name to avoid conflict
  iterator `...`*[T](a: T, b: T): T =
    var res: T = T(a)
    while res <= b:
      yield res
      inc res
  
  for i in 0...5:
    echo i
  Run

  But i want to change the "..." operator to "To". So i wrote this

  # Give it a different name to avoid conflict
  iterator `To`*[T](a: T, b: T): T =
    var res: T = T(a)
    while res <= b:
      yield res
      inc res
  
  for i in 0 To 5:
    echo i
  Run

  But it gave this error message

  Error: attempting to call routine: 'To' found 'in.To(a: T, b: T) [declared in /usercode/in.nim(2, 10)]' of kind 'iterator'

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• sky_khan (orginal) [2019-10-20T15:25:36+02:00] view original

  I dont know how 0...5 works but 0To5 is not valid syntax.

  0.To(5) or 0.To 5 works though.

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• Araq (orginal) [2019-10-20T15:26:18+02:00] view original

  To is an ordinary identifier and ordinary identifiers are never operators, operators are covered here: https://nim-lang.org/docs/manual.html#lexical-analysis-operators

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• kcvinu (orginal) [2019-10-20T15:42:09+02:00] view original

  Its not 0To5. Its 0 To 5. A space is there.

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• kcvinu (orginal) [2019-10-20T15:43:59+02:00] view original

  Thanks. Will check it. Any guidance for me in order to achieve this ?

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• Araq (orginal) [2019-10-20T16:41:32+02:00] view original

  template to(a, b): untyped = a..b
  
  for i in 0.to(5):
    echo i
  Run

  You're better off using .. though because every Nim programmer knows it and eventually it will be familiar to you too.

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• kcvinu (orginal) [2019-10-20T16:51:49+02:00] view original

  Thanks for the code. And yes, i will try to follow the Nim style.

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