The translation is fairly mechanical.
Keep in mind that in the continuation monad, return
feeds the value into the continuation.
evalStmt :: Statement -> Cont Value Value
evalStmt (Expr val) =
let res = Value val
in return res
evalStmt (Block stmts) = evalBlock stmts
evalStmt (Return val) = cont $ \_ -> Value val
evalBlock :: [Statement] -> Cont Value Value
evalBlock [] = return Undefined
evalBlock [st] = evalStmt st
evalBlock (st:rest) = evalStmt st >> evalBlock rest
evalProgram :: [Statement] -> Value
evalProgram stmts = runCont (evalBlock stmts) id
And to simulate early returns, we just ignore the continuation given to Return val
and just return the value we have.