def drop_all

bend-collections-laws-crypto@1.0.0.0 · proofs/crypto/blake/blake3/lists.bend:31

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

31def drop_all(-A: Data, +xs: List<&2,A>, +k: Nat, +h: {Nat.is_le(SC.length(A,xs),k) == True{} : Bool}) -> {SC.drop(A,xs,k) == Nil{} : List<&2,A>}:
32  match xs k:
33    case Nil{} _: {==}
34    case Con{+a,+t} 0n: Empty.absurd({SC.drop(A,Con{a,t},0n) == Nil{} : List<&2,A>},L.false_true(h))
35    case Con{+a,+t} 1n+j: drop_all(A,t,j,h)