Voting
Category
real language
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Language CHR
(CHR(Prolog)
| Date: | 06/19/06 |
| Author: | Jon Sneyers |
| URL: | http://www.cs.kuleuven.be/~jon |
| Comments: | 1 |
| Info: | http://www.cs.kuleuven.be/~dtai/projects/CHR/ |
| Score: |  (3.00 in 15 votes) |
% 99 bottles of beer, CHR(Prolog) version.
% tested in the K.U.Leuven CHR implementation in SWI-Prolog
% Mon Jun 19 14:22:05 2006 Jon Sneyers
% top-level goal: beer
:- use_module(library(chr)).
:- chr_constraint beer, beer(+int), bottle, sing,
capital, bottles, ofbeer, onwall, comma,
take_one, dotnl,
bottle_count, bottles(+int), writeresult.
:- chr_option(toplevel_show_store,off).
:- chr_option(optimize,full).
:- chr_option(debug,off).
% make 99 bottles and start singing
beer <=> beer(99), sing.
% make N bottles
makebottle @ beer(N) <=> N > 0 | bottle, beer(N-1).
endloop @ beer(_) <=> true.
% stop singing if we're already singing
% (change to simpagation rule to make the song infinite)
sing, sing <=> true.
% sing two lines
sing ==> capital, bottles, ofbeer, onwall, comma, bottles, ofbeer, dotnl,
take_one, comma, bottles, ofbeer, onwall, dotnl, nl.
% if we're still singing: sing again
sing <=> sing.
% take one bottle down
take_one, bottle <=> write('Take one down and pass it around').
% no more bottles: go to the store and start again
take_one <=> write('Go to the store and buy some more'), beer.
% print how many bottles there are in the store
bottle, bottle \ bottles <=> bottle_count, write(' bottles').
bottle \ bottles <=> write('1 bottle').
capital, bottles <=> write('No more bottles').
bottles <=> write('no more bottles').
% count the number of bottles in the store
bottle_count, bottle ==> bottles(1).
bottle_count <=> writeresult.
bottles(X), bottles(Y) <=> Z is X+Y, bottles(Z).
writeresult, bottles(N) <=> write(N).
% write stuff
onwall <=> write(' on the wall').
ofbeer <=> write(' of beer').
dotnl <=> write('.'), nl.
comma \ capital <=> true.
comma <=> write(', ').
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Comments
consider changing line 20
makebottle @ beer(N) <=> N > 0 | bottle, beer(N-1).
to
makebottle @ beer(N) <=> N > 0 | bottle, N1 is N-1, beer(N1).
because of
================================================================================
CHR compiler TYPE ERROR:
`--> Invalid functor in body goal compound(beer, 1, [compound(-, 2, [var(1, _G32266), atomic(1)], _G32266-1)], beer(_G32266-1)) of rule makebottle (line 20):
found `compound(-, 2, [var(1, _G32266), atomic(1)], _G32266-1)',
expected type `int'!
================================================================================
% bottle compiled 0.38 sec, 2,124,380 bytes
true.