Sha.nth: def of bend-collections@1.0.0.0
Import: import bend-collections@1.0.0.0/spec/crypto/sha.bend as Sha
Lines 79-88 of bend-collections@1.0.0.0/spec/crypto/sha.bend: https://jend.leeeet.dev/read.txt?path=bend-collections@1.0.0.0/spec/crypto/sha.bend&start_line=79&end_line=88

import Base

# In reverse history, index j denotes W[t-1-j]. Only valid indices are
# reached for the actual 16-word input blocks; default zero makes nth total.
def nth(history: List<&2, U32>, index: Nat) -> U32:
  match history index:
    case Nil{} _:
      0
    case w <> rest 0n:
      w
    case w <> rest 1n+p:
      nth(rest, p)

Uses (3):
  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=Base/base.bend&name=U32