dagit:
As the top search result.
This means that you can convert any list of maybes into a list of what you want. It just tosses out the Nothings.
2. Why doesn't ByteString implement 'read'? Is it just that this function (like 'input' in Python) isn't really very useful for real programs?
I think probably for things more complex than parsing ints it's best to make your own parser? I seem to recall that someone was working on a library of parsing functions based on bytestring? Maybe someone else can comment?
3. Why doesn't ByteString implement 'readDouble', etc.? That is, why are Int and Integer treated specially? Do I not need readDouble?
I think readInt was mostly implemented because integer reading was needed a lot for benchmarks and programming challenge sites and people noticed it was way slower than needed so someone put in the effort it optimize it. Once it was optimized, that must have satisfied the need for fast number reading.
There's readInt, readInteger and readDouble now, as primitives, because people ask for them.
I would agree that at least for Prelude types it would be nice to have efficient bytestring based parsers. Do we have Read/Show classes specifically for working in bytestrings? Maybe that's what the world needs in the bytestring api. Then again, I'm not really qualified to comment :) For all I know it already exists.
Data.Binary is the generic parser for bytestrings. A higher level one for parsing text (e.g. atto-parsec), might be worthwhile. -- Don