1 files changed, 26 insertions, 0 deletions
diff --git a/files/practicum/RefactorXX.dcl b/files/practicum/RefactorXX.dcl
new file mode 100644
index 0000000..4b7748f
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+++ b/files/practicum/RefactorXX.dcl
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+definition module RefactorXX
+
+::	Expr			= NR   Int
+					| VAR  Name
+					| OP   Expr Operator Expr
+					| LET  Name     Expr Expr
+::	Name		  :== String
+::	Operator		= PLUS | MIN | MUL | DIV
+::	Val a			= Result a | Undef
+
+class fail          c :: c a
+class return        c :: a -> c a
+class (>>=) infix 0 c :: (c a) (a -> c b) -> c b
+class Monad         c | return, >>= c
+class MonadFail     c | Monad, fail c
+
+instance fail   [], Val
+instance return [], Val
+instance >>=    [], Val
+
+from StdClass import class toString
+
+instance toString Expr
+free				:: Expr -> [Name]
+remove_unused_lets	:: Expr -> Expr
+eval				:: Expr -> c Int | MonadFail c