A few minor improvements before the next release

[joeyadams]

I'd like to slip these changes in before the next release, since there's a slight API change (sqlErrorDetails is now Text instead of Maybe Text).

A couple ideas taken from persistent-sqlite:

• Support optionally using the system's sqlite3 instead of the bundled one.

• Handle invalid UTF-8 a little better.

  Someone pointed out that:

  decodeUtf8 is as evil as head: their exceptions are very unhelpful.

  persistent-sqlite uses decodeUtf8With lenientDecode, which replaces invalid characters with U+FFFD (the Unicode replacement character). Because that can silently corrupt data, I took an alternative approach: throw a DecodeError whose message refers to Database.SQLite3.

  I also documented that a DecodeError may arise, and that SQLite3 does not validate UTF-8 on input.

The last commit uses sqlite3_db_handle to get the Database of a Statement when a call fails and only a Statement is available. This eliminated all cases where no details were available, so I changed sqlErrorDetails from Maybe Text to Text.

[nurpax]

Looks good. Having an option for using system's SQLite binaries should make installation easier on Windows.

[IreneKnapp]

This is good stuff, although it should probably have been about three separate pull requests. Anyway, merged. :) Sorry for the delay, I've been busy!

[nurpax]

@joeyadams @IreneKnapp Joey, do you consider your merged changes complete enough for a new direct-sqlite release? It'd be great to get this code out. I'd at least like to switch sqlite-simple to use the latest version.

[joeyadams]

I'd say it's ready. Granted, we might want to make some changes later on (e.g. upgrade SQLite to 3.7.14, and fix a couple minor build warnings), but I think we should release first.

Current master (7649ce4) builds, and tests pass, with GHC 7.6.1 and cabal-install version 0.13.3. However, there are a few minor deprecation warnings. Thanks to the fix for GHC ticket 7167, "Module Prelude' does not exportcatch'" is a warning instead of an error.

@IreneKnapp, could you update the .cabal file to describe the new changes? I'm thinking something like:

[3.0] exports lower-level bindings, uses newtypes for parameter and column index types, throws SQL exceptions that can be caught, and uses Text instead of String even for non-data strings.

Also, could you update the homepage and bug-reports links to point to Github? The current bug-reports link gives a 403.