giles da6d8e39c9 ocaml: phase 5.1 pascal.ml baseline (Pascal triangle row 10 middle = C(10,5) = 252) ...

next_row prepends 1, walks adjacent pairs (x, y) emitting x+y,
appends a final 1:

  let rec next_row prev =
    let rec aux a =
      match a with
      | [_] -> [1]
      | x :: y :: rest -> (x + y) :: aux (y :: rest)
      | [] -> []
    in
    1 :: aux prev

row n iterates next_row n times starting from [1] using a ref +
'for _ = 1 to n do r := next_row !r done'.

  row 10 = [1;10;45;120;210;252;210;120;45;10;1]
  List.nth (row 10) 5 = 252 = C(10, 5)

Exercises three-arm match including [_] singleton wildcard, x :: y
:: rest binding, and the for-loop with wildcard counter. 45 baseline
programs total.

2026-05-09 09:57:18 +00:00

276 B

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