On the other hand, it looks to me that map is somewhat more magical than the examples in perlsub; if you call 
map (sub { "1" x $_ }, (1..10));

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it returns an array of coderefs (references to subroutines) which is not at all what is needed here.

I personally believe that indeed map and its sibling grep are more magical: precisely because as I wrote in my reply to the OP they accept an expression to be evaluated for each of the other parameters. But I don't understand what you mean with "which is not at all what is needed here" because your example does exaclty what I mean: I do expect it to return a list (not an array!) of coderefs. Only, it probably does not do what you expect in that those coderefs are... all the same coderef:

C:\temp>perl -E "say for map sub {1 x $_} => 1..3"
CODE(0x182a944)
CODE(0x182a944)
CODE(0x182a944)

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This is because $_ is a package variable and those anonymous subs are not closures: when you will use one of them, its $_ will be that in scope at the moment, not the one passed to map() when it was created. To obtain that you have to close over a lexical:

C:\temp>perl -E "say for map { my $x=$_; sub {1 x $x} } 1..3"
CODE(0x23aa7c)
CODE(0x182aef4)
CODE(0x182ad74)

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Alternatively, and this is the interesting point to be noted here, Perl 5.10 and highter support lexical $_:

C:\temp>perl -E "my $_; say for map sub {1 x $_} => 1..3"
CODE(0x23a97c)
CODE(0x182a9bc)
CODE(0x183bbbc)

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--
If you can't understand the incipit, then please check the IPB Campaign.

In reply to Re^4: Generate the perl sequence 1, 11, 111, .... by blazar
in thread Generate the perl sequence 1, 11, 111, .... by alih110

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