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Re: RFC 23 (v5) Higher order functions
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From:
Damian Conway
Date:
September 19, 2000 20:49
Subject:
Re: RFC 23 (v5) Higher order functions
Message ID:
200009200349.OAA00304@indy05.csse.monash.edu.au
> Let me ask you:
>
> foo('a','b', 'c')
>
> Is 'b' the 1st parameter or the 2nd?
This is the classical mistake of confusing indices and ordinals.
The 1st argument is bound to the parameter whose index is [0],
The 2nd argument is bound to the parameter whose index is [1], etc.
So, yes, 'b' is obviously the second argument when we're speaking
in ordinal. But it is accessed as $_[1] (or ^1) when we're writing Perl.
> And when a newbie, not one of the oldtimers whose been part of
> perl6 since Damian's RFC came out. Would they think that the second
> and third arguments were added or the first and second?
Assuming they've read L<perlcurry>, they'll know that ^1 is $_[1] is
parameter [1] is the 2nd parameter. They'll know because at the very start
of L<perlcurry> I will write:
^1 means $_[1], NOT $_[0]
^1 means $_[1], NOT $_[0]
^1 means $_[1], NOT $_[0]
^1 means $_[1], NOT $_[0]
^1 means $_[1], NOT $_[0]
^1 means $_[1], NOT $_[0]
^1 means $_[1], NOT $_[0]
^1 means $_[1], NOT $_[0]
^1 means $_[1], NOT $_[0]
^1 means $_[1], NOT $_[0]
^1 means $_[1], NOT $_[0]
^1 means $_[1], NOT $_[0]
^1 means $_[1], NOT $_[0]
^1 means $_[1], NOT $_[0]
^1 means $_[1], NOT $_[0]
^1 means $_[1], NOT $_[0]
^1 means $_[1], NOT $_[0]
^1 means $_[1], NOT $_[0]
^1 means $_[1], NOT $_[0]
^1 means $_[1], NOT $_[0]
^1 means $_[1], NOT $_[0]
^1 means $_[1], NOT $_[0]
^1 means $_[1], NOT $_[0]
^1 means $_[1], NOT $_[0]
^1 means $_[1], NOT $_[0]
^1 means $_[1], NOT $_[0]
^1 means $_[1], NOT $_[0]
:-)
Damian
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