Can be shortened to: 
perl -le'$_=sprintf"%b",pop;s/../$&%8/eg;print'

[download]
Fails in case the binary expension has odd length. can be fixed like this for example: 
perl -le'$_=sprintf"%b",pop;s/..(?=(..)*$)/$&%8/eg;print' 31

[download]

update (broquaint): added formatting

In reply to Re: Re: base 4 golf by thospel
in thread base 4 golf by hv

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