delete works on a hash, not an array.

Hm. It does 'work' on an array on both 5.8.9 and 5.10.1:

C:\test>\perl32\bin\perl -Mstrict -we"my @a = 1..10; delete $a[5]; pri
+nt qq[@a]"
Use of uninitialized value in join or string at -e line 1.
1 2 3 4 5  7 8 9 10

C:\test>\perl64\bin\perl -Mstrict -we"my @a = 1..10; delete $a[5]; pri
+nt qq[@a]"
Use of uninitialized value in join or string at -e line 1.
1 2 3 4 5  7 8 9 10
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It doesn't really do what you'd hope it would do in as much as it leaves behind an undef in place of the deleted element, but there are no warnings or deprecations.