> I was in the midst of writing a reply along the same lines, so I figured I'd
> add to David's reply here. There are two characteristics I would expect from
> a method named "prefix" or "suffix".
>
> First, it should return a subsequence containing zero to count elements. (By
> contrast, something named "first" should return nil or one element, but
> certainly no more.)
>
> Second, in the case of "prefix", the first element of the subsequence (if
> any) should be the first element of the sequence; in the case of "suffix",
> the last element of the subsequence (if any) should be the last element of
> the sequence.
I would phrase these things slightly differently. In my thinking, a method with
`prefix` or `suffix` in its name:
1. Operates on a subsequence at the beginning/end of the sequence,
2. Measured *relative* to the beginning/end.
An index-based operation doesn't fit this definition because an index is not
*relative* to anything—it's an *absolute* position within the sequence.
Put another way, in my view, "prefix" and "suffix" don't merely mean "anchored
at the beginning/end". A prefix or suffix is attached to a "middle". There is
no middle in the index-based operations.
It is, of course, very possible to use methods to express what the index-based
operations do:
friends.upTo(i)
friends.through(i)
friends.from(i)
But at this point, we've basically arrived at `friends[to: i]` etc.
--
Brent Royal-Gordon
Architechies
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