Function propose_len_moves

    ∇ Z←State propose_len_moves A;Len;Moves;Rad;Progress;N;Max_N
[1]  ⍝
[2]  ⍝⍝ perform all combinations of Len moves from repertoire A.
[3]  ⍝⍝ Return the first combination (if any) that makes progress
[4]  ⍝
[5]  (Moves Len)←A ◊ Rad←Len⍴⍴Moves
[6]  N←0 ◊ Max_N←(⍴Moves)⋆Len
[7]  ⍝'Length: ' Len 'Count:' Max_N
[8]  LOOP: Z←Moves[1+Rad⊤N] ◊ →(State try_moves ∈Z)/0
[9]  →(Max_N>N←N+1)/LOOP
[10] Z←''
    ∇