[Haskell-cafe] Announce: file-location 0.2.4

Greg Weber greg at gregweber.info
Thu Aug 11 02:53:00 CEST 2011

Were you excited when Simon Marlow announced he might be able to add stack
traces to Haskell? Would you settle for just the first line of the stack
trace? It is a little known fact that template haskell exposes the file and
line number information.

file-location contains common debugging/error/exception functions and
template haskell versions that give file location information.

    > $(err "OH NO!")
    main:Main main.hs:16:1 OH NO!

    > debug [1,2,3]
    DEBUG: [1,2,3]

    > $(dbg) [1,2,3]
    DEBUG main:Main main.hs:1:3 [1,2,3]

    ($(thrwIO) AException) `catch` \e -> putStrLn ("Caught " ++ show (e ::
    Caught AException "main:Main test/main.hs:25:6"

Don't like the exception dependency? Use version 0.2.3 for now until the
exceptions are split into a separate package.
Just want the debug helpers (like the debug function) but not interested in
the template haskell? The library is already split into modules based on
dependencies. The near future plan is to separate this into separate
packages, including one with the non-TH debug helpers.

Also see the github README for more examples:

I think haskell could use a few more debug helpers. Perhaps some of these
could be pushed back into the standard distribution.

Thanks, and I am looking forward to your feedback,
Greg Weber
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