Initial import

1 files changed, 32 insertions, 0 deletions

diff --git a/lang/prolog/1.8.7/src/calc b/lang/prolog/1.8.7/src/calc
new file mode 100644
index 0000000..0ed11af
--- /dev/null
+++ b/lang/prolog/1.8.7/src/calc
@@ -0,0 +1,32 @@
+{ CALC evaluates arithmetic expressions with store } 
+ 
+calc:- eval ([], RS), write (result store), write (RS), nl. 
+ 
+eval (SI, SO):- 
+   read (CALC), nonvar (CALC), eval member (CALC, SI, SO). 
+ 
+eval member (CALC, SI, SO):- 
+   member (CALC, [stop,end,bye,eof]), SO=SI; 
+   eval (CALC,I,SI,ST), write (I), eval (ST,SO); 
+   write (error in), write (CALC), nl, eval (SI, SO). 
+ 
+eval (I, I, S, S):- integer (I). 
+eval (N, I, S, S):- atom (N), eval atom (N, I, S). 
+ 
+eval atom (N, I, S):- 
+  member (N=I, S); 
+  write ("error:  Cell"), write (N), 
+    write("not found in store. 0 substituted."), nl, I=0. 
+ 
+eval ( L+R,I,SI,SO):- eval (L,J,SI,ST), eval (R,K,ST,SO), I IS J+K. 
+eval ( L-R,I,SI,SO):- eval (L,J,SI,ST), eval (R,K,ST,SO), I IS J-K. 
+eval ( L*R,I,SI,SO):- eval (L,J,SI,ST), eval (R,K,ST,SO), I IS J*K. 
+eval ( L/R,I,SI,SO):- eval (L,J,SI,ST), eval (R,K,ST,SO), I IS J/K. 
+ 
+eval (N=O, I, SI, SO):- 
+  atom (N), eval (O,I,SI,ST), eval repl (N,I,ST,SO). 
+ 
+eval repl (N, I, [], [=(N,I)]). 
+eval repl (N, I, [=(N,_)|S], [=(N,I)|S]). 
+eval repl (N, I, [=(M,J)|SI], [=(M,J)|SO]):- eval repl (N, I, SI, SO). 
+