simp
case a
t : Tensor1D
extractlen : ℕ
fillval : FinInt 32
n : ℕ
h : n < List.length (List.replicate (min extractlen t.size0) fillval)
⊢ List.getF (List.replicate (min extractlen t.size0) fillval) n h =
    List.getF (List.take extractlen (List.replicate t.size0 fillval)) n
      (_ : n < List.length (List.take extractlen (List.replicate t.size0 fillval)))

case h_len
t : Tensor1D
extractlen : ℕ
fillval : FinInt 32
⊢ List.length (List.replicate (min extractlen t.size0) fillval) =
    List.length (List.take extractlen (List.replicate t.size0 fillval))
case a
t : Tensor1D
extractlen : ℕ
fillval : FinInt 32
n : ℕ
h : n < List.length (List.replicate (min extractlen t.size0) fillval)
⊢ List.getF (List.replicate (min extractlen t.size0) fillval) n h =
    List.getF (List.replicate t.size0 fillval) n (_ : n < List.length (List.replicate t.size0 fillval))

case h_len
t : Tensor1D
extractlen : ℕ
fillval : FinInt 32
⊢ List.length (List.replicate (min extractlen t.size0) fillval) =
    List.length (List.take extractlen (List.replicate t.size0 fillval))