RosettaCodeData/Task/Topological-sort/PicoLisp/topological-sort.l

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(de sortDependencies (Lst)
(setq Lst # Build a flat list
(uniq
(mapcan
'((L)
(put (car L) 'dep (cdr L)) # Store dependencies in 'dep' properties
(copy L) )
(mapcar uniq Lst) ) ) ) # without self-dependencies
(make
(while Lst
(ifn (find '((This) (not (: dep))) Lst) # Found non-depending lib?
(quit "Can't resolve dependencies" Lst)
(del (link @) 'Lst) # Yes: Store in result
(for This Lst # and remove from 'dep's
(=: dep (delete @ (: dep))) ) ) ) ) )