Types in `null` are treated like zero values in Go: blank string input will produce a null `null.String`, and null Strings will JSON encode to `""`. If you need zero and null treated the same, use these.
Types in `nuller` will only be considered null on null input, and will JSON encode to `null`. If you need zero and null be considered separate values, use these.
All types implement `sql.Scanner` and `driver.Valuer`, so you can use this library in place of `sql.NullXXX`. All types also implement: `encoding.TextMarshaler`, `encoding.TextUnmarshaler`, `json.Marshaler`, and `json.Unmarshaler`.
Will marshal to a blank string if null. Blank string input produces a null String. In other words, null values and empty values are considered equivalent. Can unmarshal from `sql.NullString` JSON input.
Will marshal to 0 if null. Blank string or 0 input produces a null Int. In other words, null values and empty values are considered equivalent. Can unmarshal from `sql.NullInt64` JSON input.
Unlike `null.String`, `nuller.String` will marshal to null if null. Zero (blank) input will not produce a null String. Can unmarshal from `sql.NullString` JSON input.
`json`'s `",omitempty"` struct tag does not work correctly right now. It will never omit a null or empty String. This should be [fixed in Go 1.4](https://code.google.com/p/go/issues/detail?id=4357).
