This question surfaced in discussion on PR #1 but it wasn't discussed in any depth. Here is quote and links from @cartazio:

There’s several gotchas with those algorithms for float and double.

The usual unit interval used in extent Haskell Libs is wrong.

See the commented out bit linked herein
https://github.com/haskell/random/blob/master/src/Data/Distribution/FloatingInterval.hs

@idontgetoutmuch

Here's another implementation for getting random floating point numbers

https://github.com/mokus0/random-fu/blob/69a563a7b0cf444748e4b38a8bda7ada0b9acf14/random-source/src/Data/Random/Internal/Words.hs#L103

wordToFloat :: Word64 -> Float
wordToFloat x = (encodeFloat $! toInteger (x .&. 0x007fffff {- 2^23-1 -} )) $ (-23)

I think it would be convenient to put such a function in random rather than lots of packages implementing it themselves but I don't feel strongly about it.

It seems there's general consensus that we should include generators for floating point numbers but very little discussion on implementation