mirror of
https://github.com/urbit/shrub.git
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314 lines
7.8 KiB
Plaintext
314 lines
7.8 KiB
Plaintext
|%
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::
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:: $mk-item: constructor for +ordered-map item type
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::
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++ mk-item |$ [key val] [key=key val=val]
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:: +ordered-map: treap with user-specified horizontal order
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::
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:: Conceptually smaller items go on the left, so the item with the
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:: smallest key can be popped off the head. If $key is `@` and
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:: .compare is +lte, then the numerically smallest item is the head.
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::
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++ or-map
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|* [key=mold val=mold]
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=> |%
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+$ item (mk-item key val)
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--
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:: +compare: item comparator for horizontal order
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::
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|= compare=$-([key key] ?)
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|%
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:: +check-balance: verify horizontal and vertical orderings
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::
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++ check-balance
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=| [l=(unit key) r=(unit key)]
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|= a=(tree item)
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^- ?
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:: empty tree is valid
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::
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?~ a %.y
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:: nonempty trees must maintain several criteria
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::
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?& :: if .n.a is left of .u.l, assert horizontal comparator
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::
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?~(l %.y (compare key.n.a u.l))
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:: if .n.a is right of .u.r, assert horizontal comparator
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::
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?~(r %.y (compare u.r key.n.a))
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:: if .a is not leftmost element, assert vertical order between
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:: .l.a and .n.a and recurse to the left with .n.a as right
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:: neighbor
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::
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?~(l.a %.y &((mor key.n.a key.n.l.a) $(a l.a, l `key.n.a)))
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:: if .a is not rightmost element, assert vertical order
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:: between .r.a and .n.a and recurse to the right with .n.a as
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:: left neighbor
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::
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?~(r.a %.y &((mor key.n.a key.n.r.a) $(a r.a, r `key.n.a)))
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==
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:: +put: ordered item insert
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::
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++ put
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|= [a=(tree item) =key =val]
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^- (tree item)
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:: base case: replace null with single-item tree
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::
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?~ a [n=[key val] l=~ r=~]
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:: base case: overwrite existing .key with new .val
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::
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?: =(key.n.a key) a(val.n val)
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:: if item goes on left, recurse left then rebalance vertical order
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::
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?: (compare key key.n.a)
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=/ l $(a l.a)
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?> ?=(^ l)
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?: (mor key.n.a key.n.l)
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a(l l)
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l(r a(l r.l))
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:: item goes on right; recurse right then rebalance vertical order
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::
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=/ r $(a r.a)
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?> ?=(^ r)
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?: (mor key.n.a key.n.r)
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a(r r)
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r(l a(r l.r))
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:: +peek: produce head (smallest item) or null
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::
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++ peek
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|= a=(tree item)
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^- (unit item)
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::
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?~ a ~
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?~ l.a `n.a
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$(a l.a)
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:: +pop: produce .head (smallest item) and .rest or crash if empty
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::
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++ pop
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|= a=(tree item)
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^- [head=item rest=(tree item)]
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::
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?~ a !!
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?~ l.a [n.a r.a]
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::
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=/ l $(a l.a)
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:- head.l
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:: load .rest.l back into .a and rebalance
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::
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?: |(?=(~ rest.l) (mor key.n.a key.n.rest.l))
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a(l rest.l)
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rest.l(r a(r r.rest.l))
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:: +del: delete .key from .a if it exists, producing value iff deleted
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::
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++ del
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|= [a=(tree item) =key]
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^- [(unit val) (tree item)]
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::
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?~ a [~ ~]
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:: we found .key at the root; delete and rebalance
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::
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?: =(key key.n.a)
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[`val.n.a (nip a)]
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:: recurse left or right to find .key
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::
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?: (compare key key.n.a)
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=+ [found lef]=$(a l.a)
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[found a(l lef)]
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=+ [found rig]=$(a r.a)
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[found a(r rig)]
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:: +nip: remove root; for internal use
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::
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++ nip
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|= a=(tree item)
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^- (tree item)
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::
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?> ?=(^ a)
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:: delete .n.a; merge and balance .l.a and .r.a
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::
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|- ^- (tree item)
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?~ l.a r.a
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?~ r.a l.a
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?: (mor key.n.l.a key.n.r.a)
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l.a(r $(l.a r.l.a))
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r.a(l $(r.a l.r.a))
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:: +traverse: stateful partial inorder traversal
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::
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:: Mutates .state on each run of .f. Starts at .start key, or if
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:: .start is ~, starts at the head (item with smallest key). Stops
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:: when .f produces .stop=%.y. Traverses from smaller to larger
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:: keys. Each run of .f can replace an item's value or delete the
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:: item.
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::
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++ traverse
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|* state=mold
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|= $: a=(tree item)
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=state
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f=$-([state item] [(unit val) ? state])
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==
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^+ [state a]
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:: acc: accumulator
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::
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:: .stop: set to %.y by .f when done traversing
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:: .state: threaded through each run of .f and produced by +abet
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::
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=/ acc [stop=`?`%.n state=state]
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=< abet =< main
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|%
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++ abet [state.acc a]
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:: +main: main recursive loop; performs a partial inorder traversal
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::
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++ main
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^+ .
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:: stop if empty or we've been told to stop
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::
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?~ a .
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?: stop.acc .
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:: inorder traversal: left -> node -> right, until .f sets .stop
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::
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=> left
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?: stop.acc .
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=> node
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?: stop.acc .
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right
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:: +node: run .f on .n.a, updating .a, .state, and .stop
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::
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++ node
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^+ .
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:: run .f on node, updating .stop.acc and .state.acc
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::
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=^ res acc
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?> ?=(^ a)
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(f state.acc n.a)
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:: apply update to .a from .f's product
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::
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=. a
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:: if .f requested node deletion, merge and balance .l.a and .r.a
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::
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?~ res (nip a)
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:: we kept the node; replace its .val; order is unchanged
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::
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?> ?=(^ a)
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a(val.n u.res)
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::
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..node
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:: +left: recurse on left subtree, copying mutant back into .l.a
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::
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++ left
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^+ .
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?~ a .
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=/ lef main(a l.a)
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lef(a a(l a.lef))
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:: +right: recurse on right subtree, copying mutant back into .r.a
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::
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++ right
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^+ .
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?~ a .
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=/ rig main(a r.a)
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rig(a a(r a.rig))
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--
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:: +tap: convert to list, smallest to largest
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::
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++ tap
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|= a=(tree item)
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^- (list item)
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::
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=| b=(list item)
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|- ^+ b
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?~ a b
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::
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$(a l.a, b [n.a $(a r.a)])
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:: +gas: put a list of items
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::
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++ gas
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|= [a=(tree item) b=(list item)]
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^- (tree item)
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::
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?~ b a
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$(b t.b, a (put a i.b))
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:: +uni: unify two ordered maps
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::
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:: .b takes precedence over .a if keys overlap.
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::
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++ uni
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|= [a=(tree item) b=(tree item)]
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^- (tree item)
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::
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?~ b a
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?~ a b
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?: =(key.n.a key.n.b)
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::
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[n=n.b l=$(a l.a, b l.b) r=$(a r.a, b r.b)]
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::
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?: (mor key.n.a key.n.b)
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::
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?: (compare key.n.b key.n.a)
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$(l.a $(a l.a, r.b ~), b r.b)
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$(r.a $(a r.a, l.b ~), b l.b)
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::
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?: (compare key.n.a key.n.b)
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$(l.b $(b l.b, r.a ~), a r.a)
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$(r.b $(b r.b, l.a ~), a l.a)
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::
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:: +get: get val at key or return ~
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::
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++ get
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|= [a=(tree item) b=key]
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^- (unit val)
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?~ a ~
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?: =(b key.n.a)
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`val.n.a
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?: (compare b key.n.a)
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$(a l.a)
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$(a r.a)
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::
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:: +subset: take a range excluding start and/or end and all elements
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:: outside the range
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::
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++ subset
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|= $: tre=(tree item)
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start=(unit key)
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end=(unit key)
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==
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^- (tree item)
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|^
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?: ?&(?=(~ start) ?=(~ end))
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tre
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?~ start
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(del-span tre %end end)
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?~ end
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(del-span tre %start start)
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?> (lth u.start u.end)
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=. tre (del-span tre %start start)
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(del-span tre %end end)
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::
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++ del-span
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|= [a=(tree item) b=?(%start %end) c=(unit key)]
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^- (tree item)
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?~ a a
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?~ c a
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?- b
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%start
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:: found key
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?: =(key.n.a u.c)
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(nip a(l ~))
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:: traverse to find key
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?: (compare key.n.a u.c)
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:: found key to the left of start
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$(a (nip a(l ~)))
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:: found key to the right of start
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a(l $(a l.a))
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::
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%end
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:: found key
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?: =(u.c key.n.a)
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(nip a(r ~))
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:: traverse to find key
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?: (compare key.n.a u.c)
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:: found key to the left of end
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a(r $(a r.a))
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:: found key to the right of end
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$(a (nip a(r ~)))
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==
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--
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--
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--
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