Proposal: Add concatMapM function (#2042)

[Johan Tibell]

On Jan 31, 2008 7:45 PM, Bulat Ziganshin <bulat.ziganshin at gmail.com> wrote:
> Hello Johan,
>
> Thursday, January 31, 2008, 6:19:40 PM, you wrote:
>
> >> > data Encoding = Encoding { encode :: String -> String
> >> >                          , decode :: String -> String }
>
> > With this approach I would like some facility (e.g. table) to lookup
> > common encodings as the encoding used for a particular datum is not
> > know at compile time in many applications (e.g. it's read from a HTTP
> > Content-Type header or similar.)
>
> >> lookupEncoding :: String -> Maybe Encoding
>
> you may have several libs installed each one providing its own
> set of encodings, moreover some libs (e.g. iconv-based) may provide
> this info only at run-time (i.e. in IO monad)
>
> so it have meaning to require from authors of encoding libs/modules to
> provide "dictionaries" of encodings implemented, and combine these
> dictionaries yourself:
>
> myLookup = do iconvEncodings <- IConv.lookupEncoding
>               return (stdEncodings <+> iconvEncodings <+> OtherLib.lookupEncoding)

Hi Bulat,

Sure. I would also prefer to have a minimal number of encoding
provided in a GHC library.