calculator ex

1 files changed, 47 insertions, 0 deletions

diff --git a/examples/tutorial/calculator/CalculatorC.gf b/examples/tutorial/calculator/CalculatorC.gf
new file mode 100644
index 000000000..f78d4f38b
--- /dev/null
+++ b/examples/tutorial/calculator/CalculatorC.gf
@@ -0,0 +1,47 @@
+--# -path=.:prelude
+
+concrete CalculatorC of Calculator = open Prelude in {
+
+  flags lexer=codevars ; unlexer=code ;
+
+  lincat 
+    Prog, Var = SS ; 
+    Exp = TermPrec ;
+
+  lin
+    PEmpty = ss [] ;
+    PDecl exp prog = ss ("int" ++ prog.$0 ++ "=" ++ exp.s ++ ";" ++ prog.s) ;
+    PAss vr exp prog = ss (vr.s ++ "=" ++ exp.s ++ ";" ++ prog.s) ;
+
+    EPlus  = infixl 0 "+" ;
+    EMinus = infixl 0 "-" ;
+    ETimes = infixl 1 "*" ;
+
+    EInt i = constant i.s ;
+    EVar x = constant x.s ;
+
+  oper
+    Prec : PType = Predef.Ints 2 ;
+    TermPrec : Type = {s : Str ; p : Prec} ;
+
+    usePrec : TermPrec -> Prec -> Str = \x,p ->
+      case <<x.p,p> : Prec * Prec> of {
+        <1,1> | <1,0> | <0,0> => x.s ;
+        <1,_> | <0,_>         => "(" ++ x.s ++ ")" ;
+        _ => x.s
+        } ;
+
+    mkPrec : Prec -> Str -> TermPrec = \p,s -> 
+      {s = s ; p = p} ;
+
+    constant : Str -> TermPrec = mkPrec 2 ;
+
+    infixl : Prec -> Str -> (_,_ : TermPrec) -> TermPrec = \p,f,x,y ->
+      mkPrec p (usePrec x p ++ f ++ usePrec y (nextPrec p)) ;
+
+    nextPrec : Prec -> Prec = \p -> case <p : Prec> of {
+      2 => 2 ; 
+      n => Predef.plus n 1
+      } ;
+
+}