roman.pl

COMS30106 · Mar 20, 2018 · 99b0a32 · 99b0a32
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+%% Roman numerals %%
+% adapted from https://groups.google.com/forum/#!topic/comp.compilers/g8Qvp-KGbig
+
+roman(N) --> d(N4,4),d(N3,3),d(N2,2),d(N1,1),{N is N4*1000+N3*100+N2*10+N1}.
+
+i(1) --> [i].
+i(2) --> [x].
+i(3) --> [c].
+i(4) --> [m].
+
+v(1) --> [v].
+v(2) --> [l].
+v(3) --> [d].
+
+d(0,_) --> [].
+d(1,N) --> i(N).
+d(2,N) --> i(N),i(N).
+d(3,N) --> i(N),i(N),i(N).
+d(4,N) --> i(N),v(N).
+d(5,N) --> v(N).
+d(6,N) --> v(N),i(N).
+d(7,N) --> v(N),i(N),i(N).
+d(8,N) --> v(N),i(N),i(N),i(N).
+d(9,N) --> i(N),{N1 is N+1},i(N1).