def empty_drop

bend-collections-laws-crypto@1.0.0.0 · proofs/crypto/blake/blake3/lists.bend:78

import Base
import bend-collections-laws-crypto@1.0.0.0/spec/lib/common.bend as SC

78def empty_drop(-A: Data, +xs: List<&2,A>, +k: Nat) -> {is_empty(A,SC.drop(A,xs,k)) == Nat.is_le(SC.length(A,xs),k) : Bool}:
79  match xs k:
80    case Nil{} 0n: {==}
81    case Nil{} 1n+j: {==}
82    case Con{+a,+t} 0n: {==}
83    case Con{+a,+t} 1n+j: empty_drop(A,t,j)