Blake3.tree: def of bend-collections-laws-crypto@1.0.0.0
Import: import bend-collections-laws-crypto@1.0.0.0/spec/crypto/blake/blake3.bend as Blake3
Lines 244-257 of bend-collections-laws-crypto@1.0.0.0/spec/crypto/blake/blake3.bend: https://jend.leeeet.dev/read.txt?path=bend-collections-laws-crypto@1.0.0.0/spec/crypto/blake/blake3.bend&start_line=244&end_line=257

import Base
import bend-collections-laws-crypto@1.0.0.0/src/crypto/blake/blake3/types.bend as T
import bend-collections-laws-crypto@1.0.0.0/spec/lib/common.bend as SC

# The tree over the chunk outputs xs, 1 <= |xs| <= 2^h. The chunks are its
# leaves in order; a left subtree is always complete with a power of two of
# chunks, the largest one that leaves at least one chunk to its right: with
# h = g+1 and |xs| > 2^g the left subtree takes the first 2^g chunks and the
# right one the rest, while |xs| <= 2^g (nothing left for the right) means the
# tree already fits in height g.
def tree(+h: Nat, +xs: List<&2,T.Out>) -> T.Out:
  match h xs:
    case 0n Nil{}: first(Nil{})
    case 0n Con{+x,+r}: first(Con{x,r})
    case 1n+g Nil{}: first(Nil{})
    case 1n+g Con{+x,+r}:
      +k = SC.pow2(g)
      join(tree(g,SC.take(T.Out,Con{x,r},k)),tree(g,SC.drop(T.Out,Con{x,r},k)),is_nil(SC.drop(T.Out,Con{x,r},k)))

Uses (9):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=List
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-crypto@1.0.0.0/spec/crypto/blake/blake3.bend&name=first
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-crypto@1.0.0.0/spec/crypto/blake/blake3.bend&name=is_nil
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-crypto@1.0.0.0/spec/crypto/blake/blake3.bend&name=join
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-crypto@1.0.0.0/spec/lib/common.bend&name=drop
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-crypto@1.0.0.0/spec/lib/common.bend&name=pow2
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-crypto@1.0.0.0/spec/lib/common.bend&name=take
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-crypto@1.0.0.0/src/crypto/blake/blake3/types.bend&name=Out