To paraphrase James Watson's comment in The Double Helix on Linus Pauling's comment : "The alpha helix is very interesting" , this is very interesting to those of us interested in it . A tree is equivalent to a less or more sparse array . Are there any simple algorithms for operations , eg: to "transpose" , your representations , that is , to interchange order of the nesting ? This has made me reexamine my ' flip function which I ended up deciding to just return the flip of the shorter of the 2 counts rather than what I did first , given CoSy's modulo indexing , replicate the shorter to match the longer rather than just throw an error . Here's what it currently looks like in CoSy Forth . : flip ( CSob -- CSob ) | Transpose list of 2 lists . | returns list of each item of 1th list w corresponding item of 1st subject | to the minimum length of the 2 lists . | dup @ if ;then | transpose of a simple obj is itself dup i# 0;drop | same for empty refs+> dup ['] rho 'm ,/ ['] min _./ >_ cellVecInit >aux> | ob nbdy i# 0 ?do dup i _nth refs+> aux@ i i! loop refs- aux> ;