OpenEuphoria

Suggested Extension to Euphoria language

• Posted by JEFF ZEITLIN <jeff.zeitlin at EXECNET.COM> Feb 26, 1997
• 1451 views

I was doing what I call "concept coding" today, and found that
  a lot of what I was doing for the project involved building up
  sequences from selected elements of other sequences,
  frequently within loops of various types.

  It occurred to me that an extension of the slice concept might
  come in useful here, such that if the subscript were a
  sequence of integers, it would have the effect of selecting
  those items in the sequence in the corresponding positions.
  Under such an extension, a[3..6] (legal syntax) and
  a[{3,4,5,6}] (illegal, but proposed) would be equivalent - but
  one could also write a[{1,3,4,6,8,12}] and get back a sequence
  containing only those elements, in that order.  This would
  also naturally open up the possibilities of "reverse slices"
  (i.e., a[6..3] (illegal syntax)) in the form a[{6,5,4,3}].  As
  it is, to process these "extended slices", I must place the
  desired sequence in a variable, and then loop on the index
  into the variable to build the result sequence:

  index_seq = {1,2,3,5,8}
  b = {}
  for i = 1 to length(index_seq)
        b = append(b,a[index_seq[i]])
  end for

  whereas under the proposed sequence I could say

  b = a[index_seq]

  I find this extension to be no less intuitive than the current
  sequential slice syntax (b = a[3..6]), and, as indicated, it
  seems to me to be a logical extension.

  Comments?

  N.B. for those who are curious, "concept coding" means that
  the code is essentially the core routines with hard-coded
  values (which should be parameters) to determine if the lines
  that I am thinking along are appropriate to solve the problem
  I am working on.

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Jeff Zeitlin                                      jeff.zeitlin at execnet.com
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