diff options
| -rw-r--r-- | fp2/week45/camil/RefactorX.dcl | 18 | ||||
| -rw-r--r-- | fp2/week45/camil/RefactorX.icl | 82 |
2 files changed, 100 insertions, 0 deletions
diff --git a/fp2/week45/camil/RefactorX.dcl b/fp2/week45/camil/RefactorX.dcl new file mode 100644 index 0000000..3ddc8a4 --- /dev/null +++ b/fp2/week45/camil/RefactorX.dcl @@ -0,0 +1,18 @@ +definition module RefactorX
+
+import StdEnv
+
+:: Expr = NR Int
+ | VAR Name
+ | OP Expr Operator Expr
+ | LET Name Expr Expr
+:: Name :== String
+:: Operator = PLUS | MIN | MUL | DIV
+:: Val = Result Int | Undef
+
+from StdClass import class toString
+
+instance toString Expr
+free :: Expr -> [Name]
+remove_unused_lets :: Expr -> Expr
+eval :: Expr -> Val
diff --git a/fp2/week45/camil/RefactorX.icl b/fp2/week45/camil/RefactorX.icl new file mode 100644 index 0000000..3f273e0 --- /dev/null +++ b/fp2/week45/camil/RefactorX.icl @@ -0,0 +1,82 @@ +implementation module RefactorX
+
+import StdEnv
+
+Start = map eval [E1,E2,E3,E4,E5]
+
+E1 = OP (LET "x" (OP (NR 42) MIN (NR 3)) (OP (VAR "x") DIV (NR 0)))
+ PLUS
+ (LET "y" (NR 6) (OP (VAR "y") MUL (VAR "y")))
+E2 = LET "x" (NR 42) (OP (VAR "x") PLUS (LET "x" (NR 58) (VAR "x")))
+E3 = LET "x" (NR 1) (LET "y" (NR 2) (LET "x" (NR 3) (NR 4)))
+E4 = LET "x" (NR 1) (OP (VAR "x") PLUS (VAR "y"))
+E5 = OP (LET "x" (NR 1) (VAR "x")) MUL (VAR "x")
+
+:: Expr = NR Int
+ | VAR Name
+ | OP Expr Operator Expr
+ | LET Name Expr Expr
+:: Name :== String
+:: Operator = PLUS | MIN | MUL | DIV
+:: Val = Result Int | Undef
+
+(<+) infixl 9 :: String a -> String | toString a
+(<+) str a = str +++ toString a
+
+instance toString Operator where
+ toString PLUS = "+"
+ toString MIN = "-"
+ toString MUL = "*"
+ toString DIV = "/"
+
+// expressies afdrukken:
+instance toString Expr where
+ toString (NR n) = toString n
+ toString (VAR s) = s
+ toString (LET s e1 e2) = "let " <+ s <+ " = " <+ e1 <+ " in " <+ e2
+ toString (OP e1 o e2) = bracket e1 <+ o <+ bracket e2
+ where
+ bracket :: Expr -> String
+ bracket (OP e1 o e2) = "(" <+ e1 <+ o <+ e2 <+ ")"
+ bracket (LET s e1 e2) = "(" <+ (LET s e1 e2) <+ ")"
+ bracket x = toString x
+
+// vrije variabelen:
+free :: Expr -> [Name]
+free (NR _) = []
+free (VAR s) = [s]
+free (LET s _ e2) = [n \\ n <- free e2 | n <> s]
+free (OP e1 _ e2) = (free e1) ++ (free e2)
+
+// verwijder deelexpressies met ongebruikte let-variabelen:
+remove_unused_lets :: Expr -> Expr
+remove_unused_lets (LET s e1 e2)
+| isMember s (free e2) = (LET s (remove_unused_lets e1) (remove_unused_lets e2))
+| otherwise = remove_unused_lets e2
+remove_unused_lets (OP e1 o e2) = OP (remove_unused_lets e1) o (remove_unused_lets e2)
+remove_unused_lets x = x
+
+// evaluator met tabel van naam-waarde paren:
+eval :: Expr -> Val
+eval e = fst (eval` e [])
+where
+ eval` :: Expr [(Name, Val)] -> (Val, [(Name, Val)])
+ eval` (NR n) vs = (Result n, [])
+ eval` (VAR s) vs = (find s vs, [])
+ where
+ find :: Name [(Name, Val)] -> Val
+ find _ [] = Undef
+ find s [(t,v):vs]
+ | s == t = v
+ | otherwise = find s vs
+ eval` (LET s e1 e2) vs = eval` e2 [(s,fst (eval` e1 vs)):vs]
+ eval` (OP e1 o e2) vs = (op o (fst (eval` e1 vs)) (fst (eval` e2 vs)), [])
+ where
+ op :: Operator Val Val -> Val
+ op _ Undef _ = Undef
+ op _ _ Undef = Undef
+ op PLUS (Result x) (Result y) = Result (x + y)
+ op MIN (Result x) (Result y) = Result (x - y)
+ op MUL (Result x) (Result y) = Result (x * y)
+ op DIV _ (Result 0) = Undef
+ op DIV (Result x) (Result y) = Result (x / y)
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