Parsing S Expression

Question

Given the following definitions that make up an S Expression from Prof. Yorgey's course:

data Atom = N Integer | I Ident deriving Show

and

data SExpr = A Atom | Comb [SExpr] deriving Show

What should the full data type be (in Haskell) for the following?

(bar (foo) 3 5 874)

Answer 1

I believe it would be something like

Comb
    [ A (I "bar")
    , Comb
        [ A (I "foo")
        ]
    , A (N 3)
    , A (N 5)
    , A (N 874)
    ]

Whenever you encounter an open parenthesis you would start a new Comb expression, so (foo) is Comb [A (I "foo")] while foo is simply A (I "foo").