| [] -> a
| hd :: tl -> foldi_left mapi (succ i) (mapi i a hd) tl
+let rec rev_mapi mapi i l =
+ let map i a hd = mapi i hd :: a in
+ foldi_left map i [] l
+
let rec rev_map_append map l r = match l with
| [] -> r
| hd :: tl -> rev_map_append map tl (map hd :: r)
+let rec split_at x = function
+ | l when x <= 0 -> [], l
+ | [] -> [], []
+ | hd :: tl ->
+ let l1, l2 = split_at (pred x) tl in
+ hd :: l1, l2
+
let error s = raise (Error s)
let log s = P.eprintf "MaTeX: %s\n%!" s