Diamond Kata

diamond.re

module Diamond = {
  let inc_char c => char_of_int (int_of_char c + 1);
  let rec range_rec l a b => a == b ? l @ [a] : range_rec (l @ [a]) (inc_char a) b;
  let range a b => range_rec [] a b;
  let rec replicate a s i => i < 1 ? a : replicate (a ^ s) s (i - 1);
  let addSpaces i => replicate "" " " i;
  let line p j c => {
    let cs = Char.escaped c;
    addSpaces p ^ cs ^ (j < 1 ? "" : addSpaces j ^ cs)
  };
  let createLine t i c => {
    let p = t - i - 1;
    let m = i * 2 - 1;
    line p m c
  };
  let diamond c => {
    let r = range 'A' (Char.uppercase c);
    let f = createLine (List.length r);
    let top = List.mapi f r;
    let bottom = List.tl (List.rev top);
    top @ bottom
  };
};

diamond_test.re

open Jest;
open Expect;
open! Expect.Operators;
open Diamond;

describe
  "Diamond"
  (
    fun () => {
      test "inc_char" (fun () => expect (Diamond.inc_char 'A') === 'B');
      test "range same" (fun () => expect (Diamond.range 'A' 'A') |> toEqual []);
      test "range" (fun () => expect (Diamond.range 'A' 'B') |> toEqual ['A', 'B']);
      test "range" (fun () => expect (Diamond.range 'A' 'D') |> toEqual ['A', 'B', 'C', 'D']);
      test "replicate 0" (fun () => expect (Diamond.replicate "" "1" 0) |> toEqual "");
      test "replicate 1" (fun () => expect (Diamond.replicate "" "1" 1) |> toEqual "1");
      test "replicate 111" (fun () => expect (Diamond.replicate "" "1" 3) |> toEqual "111");
      test "addSpaces 0" (fun () => expect (Diamond.addSpaces 0) |> toEqual "");
      test "addSpaces 1" (fun () => expect (Diamond.addSpaces 1) |> toEqual " ");
      test "line A" (fun () => expect (Diamond.line 0 0 'A') |> toEqual "A");
      test "line B" (fun () => expect (Diamond.line 0 1 'B') |> toEqual "B B");
      test "line B" (fun () => expect (Diamond.line 1 1 'B') |> toEqual " B B");
      test "line C" (fun () => expect (Diamond.line 0 3 'C') |> toEqual "C   C");
      test "createLine A" (fun () => expect (Diamond.createLine 1 0 'A') |> toEqual "A");
      test "createLine B" (fun () => expect (Diamond.createLine 2 1 'B') |> toEqual "B B");
      test "createLine B" (fun () => expect (Diamond.createLine 3 1 'B') |> toEqual " B B");
      test "createLine C" (fun () => expect (Diamond.createLine 3 2 'C') |> toEqual "C   C");
      test "createLine C" (fun () => expect (Diamond.createLine 4 2 'C') |> toEqual " C   C");
      test "diamond A" (fun () => expect (Diamond.diamond 'A') |> toEqual ["A"]);
      test "diamond B" (fun () => expect (Diamond.diamond 'B') |> toEqual [" A", "B B", " A"]);
      test
        "diamond C"
        (
          fun () => expect (Diamond.diamond 'C') |> toEqual ["  A", " B B", "C   C", " B B", "  A"]
        );
      test
        "diamond D"
        (
          fun () =>
            expect (Diamond.diamond 'D') |>
            toEqual ["   A", "  B B", " C   C", "D     D", " C   C", "  B B", "   A"]
        )
    }
  );