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hyphenrf's solution

to Beer Song in the OCaml Track

Published at Jul 14 2020 · 0 comments
Instructions
Test suite
Solution

Recite the lyrics to that beloved classic, that field-trip favorite: 99 Bottles of Beer on the Wall.

Note that not all verses are identical.

99 bottles of beer on the wall, 99 bottles of beer.
Take one down and pass it around, 98 bottles of beer on the wall.

98 bottles of beer on the wall, 98 bottles of beer.
Take one down and pass it around, 97 bottles of beer on the wall.

97 bottles of beer on the wall, 97 bottles of beer.
Take one down and pass it around, 96 bottles of beer on the wall.

96 bottles of beer on the wall, 96 bottles of beer.
Take one down and pass it around, 95 bottles of beer on the wall.

95 bottles of beer on the wall, 95 bottles of beer.
Take one down and pass it around, 94 bottles of beer on the wall.

94 bottles of beer on the wall, 94 bottles of beer.
Take one down and pass it around, 93 bottles of beer on the wall.

93 bottles of beer on the wall, 93 bottles of beer.
Take one down and pass it around, 92 bottles of beer on the wall.

92 bottles of beer on the wall, 92 bottles of beer.
Take one down and pass it around, 91 bottles of beer on the wall.

91 bottles of beer on the wall, 91 bottles of beer.
Take one down and pass it around, 90 bottles of beer on the wall.

90 bottles of beer on the wall, 90 bottles of beer.
Take one down and pass it around, 89 bottles of beer on the wall.

89 bottles of beer on the wall, 89 bottles of beer.
Take one down and pass it around, 88 bottles of beer on the wall.

88 bottles of beer on the wall, 88 bottles of beer.
Take one down and pass it around, 87 bottles of beer on the wall.

87 bottles of beer on the wall, 87 bottles of beer.
Take one down and pass it around, 86 bottles of beer on the wall.

86 bottles of beer on the wall, 86 bottles of beer.
Take one down and pass it around, 85 bottles of beer on the wall.

85 bottles of beer on the wall, 85 bottles of beer.
Take one down and pass it around, 84 bottles of beer on the wall.

84 bottles of beer on the wall, 84 bottles of beer.
Take one down and pass it around, 83 bottles of beer on the wall.

83 bottles of beer on the wall, 83 bottles of beer.
Take one down and pass it around, 82 bottles of beer on the wall.

82 bottles of beer on the wall, 82 bottles of beer.
Take one down and pass it around, 81 bottles of beer on the wall.

81 bottles of beer on the wall, 81 bottles of beer.
Take one down and pass it around, 80 bottles of beer on the wall.

80 bottles of beer on the wall, 80 bottles of beer.
Take one down and pass it around, 79 bottles of beer on the wall.

79 bottles of beer on the wall, 79 bottles of beer.
Take one down and pass it around, 78 bottles of beer on the wall.

78 bottles of beer on the wall, 78 bottles of beer.
Take one down and pass it around, 77 bottles of beer on the wall.

77 bottles of beer on the wall, 77 bottles of beer.
Take one down and pass it around, 76 bottles of beer on the wall.

76 bottles of beer on the wall, 76 bottles of beer.
Take one down and pass it around, 75 bottles of beer on the wall.

75 bottles of beer on the wall, 75 bottles of beer.
Take one down and pass it around, 74 bottles of beer on the wall.

74 bottles of beer on the wall, 74 bottles of beer.
Take one down and pass it around, 73 bottles of beer on the wall.

73 bottles of beer on the wall, 73 bottles of beer.
Take one down and pass it around, 72 bottles of beer on the wall.

72 bottles of beer on the wall, 72 bottles of beer.
Take one down and pass it around, 71 bottles of beer on the wall.

71 bottles of beer on the wall, 71 bottles of beer.
Take one down and pass it around, 70 bottles of beer on the wall.

70 bottles of beer on the wall, 70 bottles of beer.
Take one down and pass it around, 69 bottles of beer on the wall.

69 bottles of beer on the wall, 69 bottles of beer.
Take one down and pass it around, 68 bottles of beer on the wall.

68 bottles of beer on the wall, 68 bottles of beer.
Take one down and pass it around, 67 bottles of beer on the wall.

67 bottles of beer on the wall, 67 bottles of beer.
Take one down and pass it around, 66 bottles of beer on the wall.

66 bottles of beer on the wall, 66 bottles of beer.
Take one down and pass it around, 65 bottles of beer on the wall.

65 bottles of beer on the wall, 65 bottles of beer.
Take one down and pass it around, 64 bottles of beer on the wall.

64 bottles of beer on the wall, 64 bottles of beer.
Take one down and pass it around, 63 bottles of beer on the wall.

63 bottles of beer on the wall, 63 bottles of beer.
Take one down and pass it around, 62 bottles of beer on the wall.

62 bottles of beer on the wall, 62 bottles of beer.
Take one down and pass it around, 61 bottles of beer on the wall.

61 bottles of beer on the wall, 61 bottles of beer.
Take one down and pass it around, 60 bottles of beer on the wall.

60 bottles of beer on the wall, 60 bottles of beer.
Take one down and pass it around, 59 bottles of beer on the wall.

59 bottles of beer on the wall, 59 bottles of beer.
Take one down and pass it around, 58 bottles of beer on the wall.

58 bottles of beer on the wall, 58 bottles of beer.
Take one down and pass it around, 57 bottles of beer on the wall.

57 bottles of beer on the wall, 57 bottles of beer.
Take one down and pass it around, 56 bottles of beer on the wall.

56 bottles of beer on the wall, 56 bottles of beer.
Take one down and pass it around, 55 bottles of beer on the wall.

55 bottles of beer on the wall, 55 bottles of beer.
Take one down and pass it around, 54 bottles of beer on the wall.

54 bottles of beer on the wall, 54 bottles of beer.
Take one down and pass it around, 53 bottles of beer on the wall.

53 bottles of beer on the wall, 53 bottles of beer.
Take one down and pass it around, 52 bottles of beer on the wall.

52 bottles of beer on the wall, 52 bottles of beer.
Take one down and pass it around, 51 bottles of beer on the wall.

51 bottles of beer on the wall, 51 bottles of beer.
Take one down and pass it around, 50 bottles of beer on the wall.

50 bottles of beer on the wall, 50 bottles of beer.
Take one down and pass it around, 49 bottles of beer on the wall.

49 bottles of beer on the wall, 49 bottles of beer.
Take one down and pass it around, 48 bottles of beer on the wall.

48 bottles of beer on the wall, 48 bottles of beer.
Take one down and pass it around, 47 bottles of beer on the wall.

47 bottles of beer on the wall, 47 bottles of beer.
Take one down and pass it around, 46 bottles of beer on the wall.

46 bottles of beer on the wall, 46 bottles of beer.
Take one down and pass it around, 45 bottles of beer on the wall.

45 bottles of beer on the wall, 45 bottles of beer.
Take one down and pass it around, 44 bottles of beer on the wall.

44 bottles of beer on the wall, 44 bottles of beer.
Take one down and pass it around, 43 bottles of beer on the wall.

43 bottles of beer on the wall, 43 bottles of beer.
Take one down and pass it around, 42 bottles of beer on the wall.

42 bottles of beer on the wall, 42 bottles of beer.
Take one down and pass it around, 41 bottles of beer on the wall.

41 bottles of beer on the wall, 41 bottles of beer.
Take one down and pass it around, 40 bottles of beer on the wall.

40 bottles of beer on the wall, 40 bottles of beer.
Take one down and pass it around, 39 bottles of beer on the wall.

39 bottles of beer on the wall, 39 bottles of beer.
Take one down and pass it around, 38 bottles of beer on the wall.

38 bottles of beer on the wall, 38 bottles of beer.
Take one down and pass it around, 37 bottles of beer on the wall.

37 bottles of beer on the wall, 37 bottles of beer.
Take one down and pass it around, 36 bottles of beer on the wall.

36 bottles of beer on the wall, 36 bottles of beer.
Take one down and pass it around, 35 bottles of beer on the wall.

35 bottles of beer on the wall, 35 bottles of beer.
Take one down and pass it around, 34 bottles of beer on the wall.

34 bottles of beer on the wall, 34 bottles of beer.
Take one down and pass it around, 33 bottles of beer on the wall.

33 bottles of beer on the wall, 33 bottles of beer.
Take one down and pass it around, 32 bottles of beer on the wall.

32 bottles of beer on the wall, 32 bottles of beer.
Take one down and pass it around, 31 bottles of beer on the wall.

31 bottles of beer on the wall, 31 bottles of beer.
Take one down and pass it around, 30 bottles of beer on the wall.

30 bottles of beer on the wall, 30 bottles of beer.
Take one down and pass it around, 29 bottles of beer on the wall.

29 bottles of beer on the wall, 29 bottles of beer.
Take one down and pass it around, 28 bottles of beer on the wall.

28 bottles of beer on the wall, 28 bottles of beer.
Take one down and pass it around, 27 bottles of beer on the wall.

27 bottles of beer on the wall, 27 bottles of beer.
Take one down and pass it around, 26 bottles of beer on the wall.

26 bottles of beer on the wall, 26 bottles of beer.
Take one down and pass it around, 25 bottles of beer on the wall.

25 bottles of beer on the wall, 25 bottles of beer.
Take one down and pass it around, 24 bottles of beer on the wall.

24 bottles of beer on the wall, 24 bottles of beer.
Take one down and pass it around, 23 bottles of beer on the wall.

23 bottles of beer on the wall, 23 bottles of beer.
Take one down and pass it around, 22 bottles of beer on the wall.

22 bottles of beer on the wall, 22 bottles of beer.
Take one down and pass it around, 21 bottles of beer on the wall.

21 bottles of beer on the wall, 21 bottles of beer.
Take one down and pass it around, 20 bottles of beer on the wall.

20 bottles of beer on the wall, 20 bottles of beer.
Take one down and pass it around, 19 bottles of beer on the wall.

19 bottles of beer on the wall, 19 bottles of beer.
Take one down and pass it around, 18 bottles of beer on the wall.

18 bottles of beer on the wall, 18 bottles of beer.
Take one down and pass it around, 17 bottles of beer on the wall.

17 bottles of beer on the wall, 17 bottles of beer.
Take one down and pass it around, 16 bottles of beer on the wall.

16 bottles of beer on the wall, 16 bottles of beer.
Take one down and pass it around, 15 bottles of beer on the wall.

15 bottles of beer on the wall, 15 bottles of beer.
Take one down and pass it around, 14 bottles of beer on the wall.

14 bottles of beer on the wall, 14 bottles of beer.
Take one down and pass it around, 13 bottles of beer on the wall.

13 bottles of beer on the wall, 13 bottles of beer.
Take one down and pass it around, 12 bottles of beer on the wall.

12 bottles of beer on the wall, 12 bottles of beer.
Take one down and pass it around, 11 bottles of beer on the wall.

11 bottles of beer on the wall, 11 bottles of beer.
Take one down and pass it around, 10 bottles of beer on the wall.

10 bottles of beer on the wall, 10 bottles of beer.
Take one down and pass it around, 9 bottles of beer on the wall.

9 bottles of beer on the wall, 9 bottles of beer.
Take one down and pass it around, 8 bottles of beer on the wall.

8 bottles of beer on the wall, 8 bottles of beer.
Take one down and pass it around, 7 bottles of beer on the wall.

7 bottles of beer on the wall, 7 bottles of beer.
Take one down and pass it around, 6 bottles of beer on the wall.

6 bottles of beer on the wall, 6 bottles of beer.
Take one down and pass it around, 5 bottles of beer on the wall.

5 bottles of beer on the wall, 5 bottles of beer.
Take one down and pass it around, 4 bottles of beer on the wall.

4 bottles of beer on the wall, 4 bottles of beer.
Take one down and pass it around, 3 bottles of beer on the wall.

3 bottles of beer on the wall, 3 bottles of beer.
Take one down and pass it around, 2 bottles of beer on the wall.

2 bottles of beer on the wall, 2 bottles of beer.
Take one down and pass it around, 1 bottle of beer on the wall.

1 bottle of beer on the wall, 1 bottle of beer.
Take it down and pass it around, no more bottles of beer on the wall.

No more bottles of beer on the wall, no more bottles of beer.
Go to the store and buy some more, 99 bottles of beer on the wall.

For bonus points

Did you get the tests passing and the code clean? If you want to, these are some additional things you could try:

  • Remove as much duplication as you possibly can.
  • Optimize for readability, even if it means introducing duplication.
  • If you've removed all the duplication, do you have a lot of conditionals? Try replacing the conditionals with polymorphism, if it applies in this language. How readable is it?

Then please share your thoughts in a comment on the submission. Did this experiment make the code better? Worse? Did you learn anything from it?

Getting Started

  1. Install the Exercism CLI.

  2. Install OCaml.

  3. For library documentation, follow Useful OCaml resources.

Running Tests

A Makefile is provided with a default target to compile your solution and run the tests. At the command line, type:

make

Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.

Feedback, Issues, Pull Requests

The exercism/ocaml repository on GitHub is the home for all of the Ocaml exercises.

If you have feedback about an exercise, or want to help implementing a new one, head over there and create an issue or submit a PR. We welcome new contributors!

Source

Learn to Program by Chris Pine http://pine.fm/LearnToProgram/?Chapter=06

test.ml

(* beer-song - 2.1.0 *)
open Base
open OUnit2
open Beer_song

let zip s1 s2 =
  let rec go s1 s2 acc = match (s1,s2) with
    | ([], _) -> acc
    | (_, []) -> acc
    | (x::xs, y::ys) -> go xs ys ((x,y)::acc) in List.rev @@ go s1 s2 []

let find_diffs s1 s2 =
  let s1 = String.to_list s1 in
  let s2 = String.to_list s2 in
  let both = zip s1 s2 in
  List.find_mapi both ~f:(fun i (c1, c2) -> if Char.(c1 = c2) then None else Some (Printf.sprintf "Diff at index %d: %c <> %c" i c1 c2))

let diff_message s1 s2 = match find_diffs s1 s2 with
  | None -> if String.length s1 = String.length s2 then "" else "Lengths of expected and actual differ but have a common prefix."
  | Some m -> m

let ae exp got _test_ctxt =
  if String.(exp = got)
  then ()
  else failwith @@ "Expected differs from actual: " ^ (diff_message exp got)

let verse_tests = [
  "first generic verse" >::
  ae "99 bottles of beer on the wall, 99 bottles of beer.\nTake one down and pass it around, 98 bottles of beer on the wall."
    (recite 99 1);
  "last generic verse" >::
  ae "3 bottles of beer on the wall, 3 bottles of beer.\nTake one down and pass it around, 2 bottles of beer on the wall."
    (recite 3 1);
  "verse with 2 bottles" >::
  ae "2 bottles of beer on the wall, 2 bottles of beer.\nTake one down and pass it around, 1 bottle of beer on the wall."
    (recite 2 1);
  "verse with 1 bottle" >::
  ae "1 bottle of beer on the wall, 1 bottle of beer.\nTake it down and pass it around, no more bottles of beer on the wall."
    (recite 1 1);
  "verse with 0 bottles" >::
  ae "No more bottles of beer on the wall, no more bottles of beer.\nGo to the store and buy some more, 99 bottles of beer on the wall."
    (recite 0 1);
]


let lyrics_tests = [
  "first two verses" >::
  ae "99 bottles of beer on the wall, 99 bottles of beer.\nTake one down and pass it around, 98 bottles of beer on the wall.\n\n98 bottles of beer on the wall, 98 bottles of beer.\nTake one down and pass it around, 97 bottles of beer on the wall."
    (recite 99 2);
  "last three verses" >::
  ae "2 bottles of beer on the wall, 2 bottles of beer.\nTake one down and pass it around, 1 bottle of beer on the wall.\n\n1 bottle of beer on the wall, 1 bottle of beer.\nTake it down and pass it around, no more bottles of beer on the wall.\n\nNo more bottles of beer on the wall, no more bottles of beer.\nGo to the store and buy some more, 99 bottles of beer on the wall."
    (recite 2 3);
  "all verses" >::
  ae "99 bottles of beer on the wall, 99 bottles of beer.\nTake one down and pass it around, 98 bottles of beer on the wall.\n\n98 bottles of beer on the wall, 98 bottles of beer.\nTake one down and pass it around, 97 bottles of beer on the wall.\n\n97 bottles of beer on the wall, 97 bottles of beer.\nTake one down and pass it around, 96 bottles of beer on the wall.\n\n96 bottles of beer on the wall, 96 bottles of beer.\nTake one down and pass it around, 95 bottles of beer on the wall.\n\n95 bottles of beer on the wall, 95 bottles of beer.\nTake one down and pass it around, 94 bottles of beer on the wall.\n\n94 bottles of beer on the wall, 94 bottles of beer.\nTake one down and pass it around, 93 bottles of beer on the wall.\n\n93 bottles of beer on the wall, 93 bottles of beer.\nTake one down and pass it around, 92 bottles of beer on the wall.\n\n92 bottles of beer on the wall, 92 bottles of beer.\nTake one down and pass it around, 91 bottles of beer on the wall.\n\n91 bottles of beer on the wall, 91 bottles of beer.\nTake one down and pass it around, 90 bottles of beer on the wall.\n\n90 bottles of beer on the wall, 90 bottles of beer.\nTake one down and pass it around, 89 bottles of beer on the wall.\n\n89 bottles of beer on the wall, 89 bottles of beer.\nTake one down and pass it around, 88 bottles of beer on the wall.\n\n88 bottles of beer on the wall, 88 bottles of beer.\nTake one down and pass it around, 87 bottles of beer on the wall.\n\n87 bottles of beer on the wall, 87 bottles of beer.\nTake one down and pass it around, 86 bottles of beer on the wall.\n\n86 bottles of beer on the wall, 86 bottles of beer.\nTake one down and pass it around, 85 bottles of beer on the wall.\n\n85 bottles of beer on the wall, 85 bottles of beer.\nTake one down and pass it around, 84 bottles of beer on the wall.\n\n84 bottles of beer on the wall, 84 bottles of beer.\nTake one down and pass it around, 83 bottles of beer on the wall.\n\n83 bottles of beer on the wall, 83 bottles of beer.\nTake one down and pass it around, 82 bottles of beer on the wall.\n\n82 bottles of beer on the wall, 82 bottles of beer.\nTake one down and pass it around, 81 bottles of beer on the wall.\n\n81 bottles of beer on the wall, 81 bottles of beer.\nTake one down and pass it around, 80 bottles of beer on the wall.\n\n80 bottles of beer on the wall, 80 bottles of beer.\nTake one down and pass it around, 79 bottles of beer on the wall.\n\n79 bottles of beer on the wall, 79 bottles of beer.\nTake one down and pass it around, 78 bottles of beer on the wall.\n\n78 bottles of beer on the wall, 78 bottles of beer.\nTake one down and pass it around, 77 bottles of beer on the wall.\n\n77 bottles of beer on the wall, 77 bottles of beer.\nTake one down and pass it around, 76 bottles of beer on the wall.\n\n76 bottles of beer on the wall, 76 bottles of beer.\nTake one down and pass it around, 75 bottles of beer on the wall.\n\n75 bottles of beer on the wall, 75 bottles of beer.\nTake one down and pass it around, 74 bottles of beer on the wall.\n\n74 bottles of beer on the wall, 74 bottles of beer.\nTake one down and pass it around, 73 bottles of beer on the wall.\n\n73 bottles of beer on the wall, 73 bottles of beer.\nTake one down and pass it around, 72 bottles of beer on the wall.\n\n72 bottles of beer on the wall, 72 bottles of beer.\nTake one down and pass it around, 71 bottles of beer on the wall.\n\n71 bottles of beer on the wall, 71 bottles of beer.\nTake one down and pass it around, 70 bottles of beer on the wall.\n\n70 bottles of beer on the wall, 70 bottles of beer.\nTake one down and pass it around, 69 bottles of beer on the wall.\n\n69 bottles of beer on the wall, 69 bottles of beer.\nTake one down and pass it around, 68 bottles of beer on the wall.\n\n68 bottles of beer on the wall, 68 bottles of beer.\nTake one down and pass it around, 67 bottles of beer on the wall.\n\n67 bottles of beer on the wall, 67 bottles of beer.\nTake one down and pass it around, 66 bottles of beer on the wall.\n\n66 bottles of beer on the wall, 66 bottles of beer.\nTake one down and pass it around, 65 bottles of beer on the wall.\n\n65 bottles of beer on the wall, 65 bottles of beer.\nTake one down and pass it around, 64 bottles of beer on the wall.\n\n64 bottles of beer on the wall, 64 bottles of beer.\nTake one down and pass it around, 63 bottles of beer on the wall.\n\n63 bottles of beer on the wall, 63 bottles of beer.\nTake one down and pass it around, 62 bottles of beer on the wall.\n\n62 bottles of beer on the wall, 62 bottles of beer.\nTake one down and pass it around, 61 bottles of beer on the wall.\n\n61 bottles of beer on the wall, 61 bottles of beer.\nTake one down and pass it around, 60 bottles of beer on the wall.\n\n60 bottles of beer on the wall, 60 bottles of beer.\nTake one down and pass it around, 59 bottles of beer on the wall.\n\n59 bottles of beer on the wall, 59 bottles of beer.\nTake one down and pass it around, 58 bottles of beer on the wall.\n\n58 bottles of beer on the wall, 58 bottles of beer.\nTake one down and pass it around, 57 bottles of beer on the wall.\n\n57 bottles of beer on the wall, 57 bottles of beer.\nTake one down and pass it around, 56 bottles of beer on the wall.\n\n56 bottles of beer on the wall, 56 bottles of beer.\nTake one down and pass it around, 55 bottles of beer on the wall.\n\n55 bottles of beer on the wall, 55 bottles of beer.\nTake one down and pass it around, 54 bottles of beer on the wall.\n\n54 bottles of beer on the wall, 54 bottles of beer.\nTake one down and pass it around, 53 bottles of beer on the wall.\n\n53 bottles of beer on the wall, 53 bottles of beer.\nTake one down and pass it around, 52 bottles of beer on the wall.\n\n52 bottles of beer on the wall, 52 bottles of beer.\nTake one down and pass it around, 51 bottles of beer on the wall.\n\n51 bottles of beer on the wall, 51 bottles of beer.\nTake one down and pass it around, 50 bottles of beer on the wall.\n\n50 bottles of beer on the wall, 50 bottles of beer.\nTake one down and pass it around, 49 bottles of beer on the wall.\n\n49 bottles of beer on the wall, 49 bottles of beer.\nTake one down and pass it around, 48 bottles of beer on the wall.\n\n48 bottles of beer on the wall, 48 bottles of beer.\nTake one down and pass it around, 47 bottles of beer on the wall.\n\n47 bottles of beer on the wall, 47 bottles of beer.\nTake one down and pass it around, 46 bottles of beer on the wall.\n\n46 bottles of beer on the wall, 46 bottles of beer.\nTake one down and pass it around, 45 bottles of beer on the wall.\n\n45 bottles of beer on the wall, 45 bottles of beer.\nTake one down and pass it around, 44 bottles of beer on the wall.\n\n44 bottles of beer on the wall, 44 bottles of beer.\nTake one down and pass it around, 43 bottles of beer on the wall.\n\n43 bottles of beer on the wall, 43 bottles of beer.\nTake one down and pass it around, 42 bottles of beer on the wall.\n\n42 bottles of beer on the wall, 42 bottles of beer.\nTake one down and pass it around, 41 bottles of beer on the wall.\n\n41 bottles of beer on the wall, 41 bottles of beer.\nTake one down and pass it around, 40 bottles of beer on the wall.\n\n40 bottles of beer on the wall, 40 bottles of beer.\nTake one down and pass it around, 39 bottles of beer on the wall.\n\n39 bottles of beer on the wall, 39 bottles of beer.\nTake one down and pass it around, 38 bottles of beer on the wall.\n\n38 bottles of beer on the wall, 38 bottles of beer.\nTake one down and pass it around, 37 bottles of beer on the wall.\n\n37 bottles of beer on the wall, 37 bottles of beer.\nTake one down and pass it around, 36 bottles of beer on the wall.\n\n36 bottles of beer on the wall, 36 bottles of beer.\nTake one down and pass it around, 35 bottles of beer on the wall.\n\n35 bottles of beer on the wall, 35 bottles of beer.\nTake one down and pass it around, 34 bottles of beer on the wall.\n\n34 bottles of beer on the wall, 34 bottles of beer.\nTake one down and pass it around, 33 bottles of beer on the wall.\n\n33 bottles of beer on the wall, 33 bottles of beer.\nTake one down and pass it around, 32 bottles of beer on the wall.\n\n32 bottles of beer on the wall, 32 bottles of beer.\nTake one down and pass it around, 31 bottles of beer on the wall.\n\n31 bottles of beer on the wall, 31 bottles of beer.\nTake one down and pass it around, 30 bottles of beer on the wall.\n\n30 bottles of beer on the wall, 30 bottles of beer.\nTake one down and pass it around, 29 bottles of beer on the wall.\n\n29 bottles of beer on the wall, 29 bottles of beer.\nTake one down and pass it around, 28 bottles of beer on the wall.\n\n28 bottles of beer on the wall, 28 bottles of beer.\nTake one down and pass it around, 27 bottles of beer on the wall.\n\n27 bottles of beer on the wall, 27 bottles of beer.\nTake one down and pass it around, 26 bottles of beer on the wall.\n\n26 bottles of beer on the wall, 26 bottles of beer.\nTake one down and pass it around, 25 bottles of beer on the wall.\n\n25 bottles of beer on the wall, 25 bottles of beer.\nTake one down and pass it around, 24 bottles of beer on the wall.\n\n24 bottles of beer on the wall, 24 bottles of beer.\nTake one down and pass it around, 23 bottles of beer on the wall.\n\n23 bottles of beer on the wall, 23 bottles of beer.\nTake one down and pass it around, 22 bottles of beer on the wall.\n\n22 bottles of beer on the wall, 22 bottles of beer.\nTake one down and pass it around, 21 bottles of beer on the wall.\n\n21 bottles of beer on the wall, 21 bottles of beer.\nTake one down and pass it around, 20 bottles of beer on the wall.\n\n20 bottles of beer on the wall, 20 bottles of beer.\nTake one down and pass it around, 19 bottles of beer on the wall.\n\n19 bottles of beer on the wall, 19 bottles of beer.\nTake one down and pass it around, 18 bottles of beer on the wall.\n\n18 bottles of beer on the wall, 18 bottles of beer.\nTake one down and pass it around, 17 bottles of beer on the wall.\n\n17 bottles of beer on the wall, 17 bottles of beer.\nTake one down and pass it around, 16 bottles of beer on the wall.\n\n16 bottles of beer on the wall, 16 bottles of beer.\nTake one down and pass it around, 15 bottles of beer on the wall.\n\n15 bottles of beer on the wall, 15 bottles of beer.\nTake one down and pass it around, 14 bottles of beer on the wall.\n\n14 bottles of beer on the wall, 14 bottles of beer.\nTake one down and pass it around, 13 bottles of beer on the wall.\n\n13 bottles of beer on the wall, 13 bottles of beer.\nTake one down and pass it around, 12 bottles of beer on the wall.\n\n12 bottles of beer on the wall, 12 bottles of beer.\nTake one down and pass it around, 11 bottles of beer on the wall.\n\n11 bottles of beer on the wall, 11 bottles of beer.\nTake one down and pass it around, 10 bottles of beer on the wall.\n\n10 bottles of beer on the wall, 10 bottles of beer.\nTake one down and pass it around, 9 bottles of beer on the wall.\n\n9 bottles of beer on the wall, 9 bottles of beer.\nTake one down and pass it around, 8 bottles of beer on the wall.\n\n8 bottles of beer on the wall, 8 bottles of beer.\nTake one down and pass it around, 7 bottles of beer on the wall.\n\n7 bottles of beer on the wall, 7 bottles of beer.\nTake one down and pass it around, 6 bottles of beer on the wall.\n\n6 bottles of beer on the wall, 6 bottles of beer.\nTake one down and pass it around, 5 bottles of beer on the wall.\n\n5 bottles of beer on the wall, 5 bottles of beer.\nTake one down and pass it around, 4 bottles of beer on the wall.\n\n4 bottles of beer on the wall, 4 bottles of beer.\nTake one down and pass it around, 3 bottles of beer on the wall.\n\n3 bottles of beer on the wall, 3 bottles of beer.\nTake one down and pass it around, 2 bottles of beer on the wall.\n\n2 bottles of beer on the wall, 2 bottles of beer.\nTake one down and pass it around, 1 bottle of beer on the wall.\n\n1 bottle of beer on the wall, 1 bottle of beer.\nTake it down and pass it around, no more bottles of beer on the wall.\n\nNo more bottles of beer on the wall, no more bottles of beer.\nGo to the store and buy some more, 99 bottles of beer on the wall."
    (recite 99 100);
]



let () =
  run_test_tt_main (
    "beer song tests" >:::
    List.concat [
      verse_tests;
      lyrics_tests;
    ]
  )
let rec recite from until =
    let num = function
      | -1 -> "99 bottles of beer"
      | 0  -> "no more bottles of beer"
      | 1  -> "1 bottle of beer"
      | n  -> (string_of_int n) ^ " bottles of beer"
    in
    let res = function
      | 0 -> "Go to the store and buy some more, "
      | 1 -> "Take it down and pass it around, "
      | _ -> "Take one down and pass it around, "
    in
    let sing i = String.capitalize_ascii (num i) 
                 ^ " on the wall, " ^ num i ^ ".\n"
                 ^ res i ^ num (i-1) ^ " on the wall."
    in
    let rec recite' ?(s="") from until =
        match from, until with
        | _, 1 | 0, _ -> s ^ sing from
        | _           -> recite' ~s:(s ^ sing from ^ "\n\n") (from-1) (until-1)
    in
    recite' from until

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