[Haskell] modern language design, stone age tools

[Alastair Reid]

> [...]
>   2.  Use the mapException trick to annotate exceptions as they
>       travel up the stack (see Alastair Reid's message).
> [...]
> (2) requires that you add lots of annotations to your code, so it's not
> entirely satisfactory for that reason.

Would it be possible to generalise ghc's -prof-all mechanism so that 
annotations could be added automatically.  For example, suppose I have
an annotation function 

  Debug.Callstack.callstack :: ModuleName -> LineNumber -> a -> a

Then, if I compile with:

  ghc -annotate=Debug.Callstack.callstack Foo.hs

then ghc could add

  import Debug.Callstack(callstack)

to the import list and transform every top level function body
as follows:

  foo (x:xs) = ..
  foo []     = ...
=>
  foo arg = callstack 
              "Foo"  -- module name  
              42     -- line number
              (foo' arg)
  foo' (x:xs) = ..
  foo' []     = ..

--
Alastair