I'm trying to do the following from Chapter 5 of "Real World Haskell":

Our choice of naming for the source file and function is deliberate. To create an executable, ghc expects a module named Main that contains a function named main. The main function is the one that will be called when we run the program once we've built it. 6 comments

ghc -o simple Main.hs SimpleJSON.o

---from http://book.realworldhaskell.org/read/writing-a-library-working-with-json-data.html

When I do that, I get this error:

C:\ch05>ghc -o simple Main.hs SimpleJSON.o
[2 of 2] Compiling Main ( Main.hs, Main.o )
Linking simple.exe ...
SimpleJSON.o:fake:(.data+0x0): multiple definition of `SimpleJSON_getArray_closure'
.\SimpleJSON.o:fake:(.data+0x0): first defined here
SimpleJSON.o:fake:(.text+0x54): multiple definition of `SimpleJSON_getArray_info'
.\SimpleJSON.o:fake:(.text+0x54): first defined here
SimpleJSON.o:fake:(.data+0x4): multiple definition of `SimpleJSON_getObject_closure'
.\SimpleJSON.o:fake:(.data+0x4): first defined here

What's going wrong here?