1. Task Oriented Programming in using Rinus Plasmeijer – Bas Lijnse - Peter Achten Pieter Koopman - Steffen Michels - Jurriën Stutterheim Jan Martin Jansen (NLDA) - Laszlo Domoszlai (ELTE) LIGRETTO CASE STUDY 1

2. Ligretto (slightly simplified version) A card game for 2 upto 4 players Card attributes: numbered(1.. 10) front color(red, green, blue, yellow) back color(red, green, blue, yellow) Each player has 40 cards: of each color all possible 10 values 2

3. Ligretto: initial set-up (4 players) 3 middle 3 10 1 row 2 ligretto (10 cards) - hand (concealed, discard)

4. Ligretto: play the game 4 middle 3 10 1 row 2 ligretto (10 cards) - hand (concealed, discard) only cards from row and discard can be placed in middle new pile in middle starts with card value 1 on a middle pile only a card with same front color and value 1 higher can be placed cards taken from row are immediately replaced by top card from ligretto pile flip top 3 concealed cards to discard pile if concealed pile is empty, shuffle discard pile and move to concealed pile game ends as soon as first ligretto pile is empty

5. Getting started: ligretto.dcl :: NrOfPlayers:== Int :: Middle:== [Pile] :: Pile:== [Card] :: Card = { back:: Color, front:: Color, nr:: Int } :: SideUp = Front | Back :: Color = Red | Green | Blue | Yellow :: Player = { color:: Color, row:: Row, ligretto:: Pile, hand:: Hand } :: Row:== [Card] :: Hand = { conceal:: Pile, discard:: Pile } 5

6. Getting started: ligretto.dcl nr_of_cards_in_row:: NrOfPlayers-> Int colors:: NrOfPlayers-> [Color] initial_player:: NrOfPlayers Color Int-> Player row_card:: Int Player-> Card move_ligretto_card_to_row:: Int Player-> Player top_discard:: Player-> Maybe Card shuffle_hand:: Int Player-> Player remove_top_of_discard:: Player-> Player swap_discards:: Player-> Player card_matches_top_of_pile:: Card Pile-> Bool 6

7. Getting started: ligrettoTOP.icl view_card:: SideUp Card -> HtmlTag play_ligretto:: Task Color 7