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10289 :: Call iterator from within iterator

• smsifmjxtzggadeh (orginal) [2023-06-21T04:41:21+02:00] view original

  I want to call 2 different iterators conditionally:

  import os
  
  type FsOrTest* = object
    case kind: bool
    of true: dir: string
    of false: testFiles: seq[string]
  
  iterator walk*(dir: FsOrTest): string =
    case dir.kind
    of true: dir.dir.walkDirRec()
    of false: dir.testSources.items()
  Run

  But it seems like the compiler doesn't like the types:

  
  /home/xxx/dev/playground/nim/weblang/src/example.nim(10, 19) Error: attempting to call routine: 'walkDirRec'
    found os.walkDirRec(dir: string, yieldFilter: set[PathComponent], followFilter: set[PathComponent], relative: bool, checkDir: bool) [iterator declared in /home/xxx/.choosenim/toolchains/nim-1.6.12/lib/pure/os.nim(2371, 10)]
  Run

  Is there any way to make this work or do I have to use a macro?

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• demotomohiro (orginal) [2023-06-21T05:33:35+02:00] view original

  Please read this: https://nim-lang.org/docs/manual.html#iterators-and-the-for-statement

  iterators are not used like procedures.

  iterator m2(x: int): int =
    for i in 1..x:
      if i mod 2 == 0:
        yield i
  
  iterator m3(x: int): int =
    for i in 1..x:
      if i mod 3 == 0:
        yield i
  
  iterator m(m, x: int): int =
    if m == 2:
      for i in m2(x):
        yield i
    else:
      for i in m3(x):
        yield i
  
  for i in m(2, 12):
    echo i
  Run

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• smsifmjxtzggadeh (orginal) [2023-06-21T05:48:42+02:00] view original

  So a few paragraphs later when it says: > 3. Neither inline nor closure iterators can be (directly)* recursive. That doesn't mean they're callable?

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• smsifmjxtzggadeh (orginal) [2023-06-21T06:15:51+02:00] view original

  I'll just use a macro. I would just prefer the editor extension to be able to check the types.

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• Yardanico (orginal) [2023-06-21T06:23:38+02:00] view original

  You could always just do a for elem in iter: yield elem in your own iterator to yield from other ones.

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• smsifmjxtzggadeh (orginal) [2023-06-21T06:35:57+02:00] view original

  Yeah that's what I'm doing now. I didn't read the code in the first response carefully because I thought they were just copying from the manual that I had already poured over.

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