Ever wondered how to write a tile-matching game (like Candy Crush and the earlier Bejeweled)? Traditionally game developers would write a game - the graphics, state, and user interaction - in an imperative style, but recently the functional approach is getting more popular. Hakim Cassimally (BBC, Manchester LambdaLounge) has been exploring the process of developing a tile-matching game in Clojure. He'll present present some of the basics of modelling the game grid, and playing a basic event loop, introducing some important concepts in functional programming and simple game development. This is a beginner-friendly talk, originally given at def_shef 43 in Sheffield UK, Tuesday 9th January 2018.

1. Writing a
Tile-Matching Game
FP Style
Hakim Cassimally
@osfameron, @lambdamcr

4. (({:colour :red} {:colour :red} {:colour :red} {:colour :blue} {:colour :blue})
({:colour :green} {:colour :green} {:colour :red} {:colour :red} {:colour :blue})
({:colour :red} {:colour :green} {:colour:blue} {:colour :blue} {:colour :blue})
({:colour :green} {:colour :green} {:colour :green} {:colour :green} {:colour :blue})
({:colour :red} {:colour :green} {:colour :green} {:colour :red} {:colour :blue}))

6. {:colour :blue
:type :candy}

7. Match 3

8. (map (partial partition-by :colour))

9. (map (partial partition-by :colour))

10. (map match)
(defn match [groups]
(filter
#(>= (count %) 3)
groups))

11. (map match)
(defn match [groups]
(filter
#(>= (count %) 3)
groups))

12. (filter seq)

13. Er...

22. [0 0][

23. [0 0][ [1 0]

24. [0 0][ [1 0] [2 0]

25. [0 0][ [1 0] [2 0] [3 0]

26. [0 0][ [1 0] [2 0] [3 0] [4 0] ]
zip
(defn zip [list1 list2]
(map vector list1 list2))

27. (defn zip-over-grid [list1 list2]
(map zip list1 list2))

28. (zip )

30. (zip )

32. (zip )

34. (zip )

37. (repeat (range)) (map repeat (range))
...
...
...
...
...
...
...
...
...
...
...
...

38. ...
...
...
...
...
...
+

39. =

42. (defn transpose [m]
(apply map vector m))

47. (defn points [runs]
(->> runs
(map count)
(apply +)))
= 19

49. Filling

50. Filling

51. Filling

52. Filling
er....?

53. Filling

54. Filling

55. Filling

56. Filling

57. Filling

58. Filling

59. Filling

60. State or Change?

61. State or Change?

62. State or Change?
{:colour :blue
:pos [0 1]
:to [1 1]
:animate :fall}

63. Display
User
Input
Check
Matches
Remove
Matches
Adjust
Score
Fall/Fill
(animate)
{:score 0}
:grid
}

64. {:score 0}
:grid
}
Display
User
Input
Check
Matches
Remove
Matches
Adjust
Score
Fall/Fill
(animate)

65. Display
User
Input
Check
Matches
Remove
Matches
Adjust
Score
Fall/Fill
(animate)
{:score 0}
:grid
:matches
}

66. Display
User
Input
Check
Matches
Remove
Matches
Adjust
Score
Fall/Fill
(animate)
{:score 0}
:grid
:matches
}

67. Display
User
Input
Check
Matches
Remove
Matches
Adjust
Score
Fall/Fill
(animate)
{:score 5}
:grid
}

68. Display
User
Input
Check
Matches
Remove
Matches
Adjust
Score
Fall/Fill
(animate)
{:score 5}
:grid
}

69. Display
User
Input
Check
Matches
Remove
Matches
Adjust
Score
Fall/Fill
(animate)
{:score 5}
:grid
}

70. THANK YOU!
Any Questions?