Dear Sven,
However for the other parameters, I use empty values: 3) emptyGlobalRdrEnv 4) emptyTypeEnv This actually works (at least for the simple cases I have tested). But it seems wrong to me to pass two empty environments. Can I somehow obtain valid environments?
(disclaimer: I am _very_ new to this!) You may be able to extract those fields from the "ModGuts"obtained by compiling the file that you are traversing.
Another question: Why is dsExpr monadic? What side effects could there possibly be?
The desugaring process (of which dsExpr is a part) creates a bunch of distinct ("fresh") names. To do so it needs to tap into the Unique supply (see newUniqueId.) In addition, the DsM tracks some environments, source locations (getSrcSpanDs, putSrcSpanDs) etc... Ranjit.