deq (de-queue) and pop should fail on empty quotes.
This is required to preserve a symmetry for something like [ 1 2 3 ] deq enq and [ 1 2 3 ] pop push.
This is especially important since code like 1 [ ] deq enq should result in an error before enq can run. Ending up with [ 1 ] would be surprising, and this is even more surprising if it's used by a command relies on deq/enq in ways that a caller can't know.
booniepepper
commented
1 year ago
deq(de-queue) andpopshould fail on empty quotes.This is required to preserve a symmetry for something like
[ 1 2 3 ] deq enqand[ 1 2 3 ] pop push.This is especially important since code like
1 [ ] deq enqshould result in an error beforeenqcan run. Ending up with[ 1 ]would be surprising, and this is even more surprising if it's used by a command relies ondeq/enqin ways that a caller can't know.