[perl #77074] lazy rw in map

# New Ticket Created by  Francesco Rivetti 
# Please include the string:  [perl #77074]
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# <URL: http://rt.perl.org/rt3/Ticket/Display.html?id=77074 >


map-ed items are rw and map results are lazy, but the "lazy thing" is 
bound only to the output:

my @in = 1..4;
my @out := @in.map({$_*=10;});
say @in[1]; # expected 20, got 2
say @out[2]; # expected 30, got 30
say @in[1]; # got 20 now but may depend on implementation i think

personally i expected that -- with the introduction of rw trait on 
blocks -- for and map aren't aliasing anymore by default

• [perl #77074] lazy rw in map by Francesco Rivetti