Just finished writing the tests for reading and writing files. You can check the script below. With the exception of making the connection syntax consistent with the rest of it, I am going to consider this feature complete, the next things to is to work on deployment (basically, a tool that allows to run the script :-) ).

[DelimitedRecord("\t")]
class Customers:
    public OrderID as int
    public CustomerID as string
    public EmployeeID as int

connection(
    "Database",
    ConnectionType: SqlConnection,
    ConnectionString: "Data Source=localhost;Initial Catalog=ETL_Test; Integrated Security=SSPI;"
    )
source OrdersFromDatabase, Connection="Database":
    Command: "SELECT OrderID, CustomerID, EmployeeID FROM Orders"

destination OrdersFile:
    initialize:
        Parameters.File = Write(Customers).To("output.txt")
    onRow:
        cust = Customers(
            OrderID: Row.OrderID,
            CustomerID: Row.CustomerID,
            EmployeeID: Row.EmployeeID
            )
        Parameters.File.Write(cust)
    cleanUp:
        Parameters.File.Dispose()

pipeline OutputOrders:
    OrdersFromDatabase >> OrdersFile
target default:
    Execute("OutputOrders")