Hi,
For homework help I suggest you read
http://haskell.org/haskellwiki/Homework_help and follow the links
listed there.
Thanks, Neil
2010/12/5 Suresh <vai.csse(a)gmail.com>:
> Dear Sir,
>
> My be this question will be funny for you but I am new in Haskel and
> got only few lection and now I have to solve the question as test. Please
> let me know about suitable api for this question. We have wrong code and
> there is some test. Have to find out needed or suitable api and using these
> we have to pass all the test. But still I am so poor on Haskel. Please give
> me your good idea and material for this question. IF possible please give
> some example to solve this problem.
>
> module Grammar where
>
> import Data.Set (Set)
> import qualified Data.Set as Set
> import Prelude hiding (Int)
>
> import Test.HUnit
>
> data Term = Int Integer
> | Atom String
> | Var String
> | Pair (Term, Term)
> | Tuple [Term]
>
> data Expr = Term Term
> | Fun [Term] [Expr]
> | Apply Expr [Expr]
> | Assign Term Expr
>
> boundVariables :: Expr -> Set String
> boundVariables _ = Set.empty
> fromList:: Map X Y -> [(X, Y)]
>
> freeVariables :: Expr -> Set String
> freeVariables _ = Set.empty
>
> tests =
> let bv = boundVariables
> fv = freeVariables
> -- e0 := 'fun () -> ok end'
> e0 = Fun [] [Term (Atom "ok")]
> -- e1 := 'foo'
> e1 = Term (Atom "foo")
> -- e2 := 'fun (X, Y) -> F(X) end'
> e2 = Fun [Var "X", Var "Y"]
> [Apply (Term (Var "F")) [Term (Var "X")]]
> -- e3 := 'fun (true) -> F = fun (X) -> Mul(X, X) end, Add(F(X), 10)
> end'
> e3 = Fun [Atom "true"] [
> Assign (Var "F")
> (Fun [Var "X"] [
> Apply (Term (Var "Mul")) [
> Term (Var "X"),
> Term (Var "X")
> ]
> ]),
> Apply (Term (Var "Add")) [
> Apply (Term (Var "F")) [
> Term (Var "X")
> ],
> Term (Int 10)
> ]
> ]
> -- e4 := 'fun () -> F(X), F = G end'
> e4 = Fun [] [
> Apply (Term (Var "F")) [
> Term (Var "X")
> ],
> Assign (Var "F") (Term (Var "G"))
> ]
> -- e5 := 'fun () -> F = G, F(X) end'
> e5 = Fun [] [
> Assign (Var "F") (Term (Var "G")),
> Apply (Term (Var "F")) [
> Term (Var "X")
> ]
> ] in
> runTestTT (test [
> bv e1 ~=? Set.empty
> , fv e1 ~=? Set.empty
> , bv e2 ~=? Set.fromList ["X", "Y"]
> , fv e2 ~=? Set.fromList ["F"]
> , bv e3 ~=? Set.fromList ["X", "F"]
> , fv e3 ~=? Set.fromList ["Mul", "Add", "X"]
> , bv e4 ~=? Set.fromList ["F"]
> , fv e4 ~=? Set.fromList ["F", "G", "X"]
> , bv e5 ~=? Set.fromList ["F"]
> , fv e5 ~=? Set.fromList ["G", "X"]
> ])
>
>
>
>
> Best regards
> Suresh
