From a7d7542dc646a5fd124ef71e71ce260889f1701b Mon Sep 17 00:00:00 2001
From: Camil Staps
Date: Tue, 2 Feb 2016 19:24:50 +0100
Subject: Moved to 1415 directory

---
 1415/fp2/week45/mart/RefactorX.icl | 72 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 72 insertions(+)
 create mode 100644 1415/fp2/week45/mart/RefactorX.icl

(limited to '1415/fp2/week45/mart/RefactorX.icl')

diff --git a/1415/fp2/week45/mart/RefactorX.icl b/1415/fp2/week45/mart/RefactorX.icl
new file mode 100644
index 0000000..c74df08
--- /dev/null
+++ b/1415/fp2/week45/mart/RefactorX.icl
@@ -0,0 +1,72 @@
+// Mart Lubbers s4109503, Camil Staps s4498062
+
+implementation module RefactorX
+
+import StdEnv
+
+//Start = map toString [E1,E2,E3,E4,E5]
+//Start = map free [E1,E2,E3,E4,E5]
+//Start = map toString (map remove_unused_lets [E1,E2,E3,E4,E5])
+Start = map eval [E1,E2,E3,E4,E5]
+	where
+		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")
+
+(<+) infixl 9 :: String a -> String | toString a
+(<+) str a = str +++ toString a
+
+instance toString Operator where
+	toString PLUS = "+"
+	toString MIN = "-"
+	toString MUL = "*"
+	toString DIV = "/"
+ 
+instance toString Expr where
+	toString (NR n) = toString n
+	toString (VAR v) = v
+	toString (LET n e1 e2) = "(let " <+ n <+ "=" <+ e1 <+ " in " <+ e2 <+ ")"
+	toString (OP e1 o e2) = bracket e1 <+ o <+ bracket e2
+		where
+			bracket :: Expr -> String
+			bracket (OP e1 o e2) = "(" <+ (OP e1 o e2) <+ ")"
+			bracket e = toString e
+
+free:: Expr -> [Name]
+free (NR n) = [] 
+free (VAR v) = [v]
+free (OP e1 o e2) = removeDup (free e1 ++ free e2)
+free (LET n e1 e2) = removeMember n (free e2)
+
+remove_unused_lets:: Expr -> Expr
+remove_unused_lets (LET n e1 e2)
+| isMember n (free e2) = (LET n (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 e = e
+
+apply:: Operator Val Val -> Val
+apply _ Undef _ = Undef
+apply _ _ Undef = Undef
+apply DIV _ (Result 0) = Undef
+apply o (Result e1) (Result e2) = Result (apply` o e1 e2)
+	where 
+		apply`:: Operator -> Int Int -> Int
+		apply` PLUS = +
+		apply` MIN = -
+		apply` MUL = *
+		apply` DIV = /
+
+eval:: Expr -> Val
+eval e = eval` e []
+	where
+		eval`:: Expr [(Name, Val)] -> Val
+		eval` (NR n) _ = Result n
+		eval` (VAR v) [] = Undef
+		eval` (VAR v) [(n, e):xs]
+		| v == n = e
+		| otherwise = eval` (VAR v) xs
+		eval` (OP e1 o e2) xs = apply o (eval` e1 xs) (eval` e2 xs)
+		eval` (LET n e1 e2) xs = eval` e2 [(n, eval` e1 xs):xs]
-- 
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