Set KEEP on constant split
Optimize foreach on array.
Execute all BEGINs and ENDs.
Make a good way to determine if *.pl is being executed directly.
Make specialized allocators.
Optimize switches.
Do debugger
Cache eval tree
Implement eval once
Cache m//g state
rcatmaybe
Fix length($&)
eval {} coredump

make tr/// return histogram in list context?
Do anything with "hint"?
When does split() go to @_?
undef wantarray in void context?