Documentation

Encoding function.

This function allocates enough space to hold twice the size of the indata (or at least 512 bytes) and then encodes as much as possible of the indata. That means there is a risk that the encoded data won't fit and in that case the second part of the pair contains the remainder of the indata.

>>> qp_enc $ Data.ByteString.Char8.pack "="
("=3D","")
>>> snd $ qp_enc $ Data.ByteString.Char8.pack $ Data.List.take 171 $ repeat '='
"="

Decoding function.

>>> qp_dec $ Data.ByteString.Char8.pack "foobar"
Right "foobar"
>>> qp_dec $ Data.ByteString.Char8.pack "1=20+=201=20=3D=202"
Right "1 + 1 = 2"

The input data is allowed to use lowercase letters in the hexadecimal representation of an octets value, even though the standard says that only uppercase letters may be used:

>>> qp_dec $ Data.ByteString.Char8.pack "=3D"
Right "="
>>> qp_dec $ Data.ByteString.Char8.pack "=3d"
Right "="

It also allows the input to encode _all_ octets in the hexadecimal representation:

>>> qp_dec $ Data.ByteString.Char8.pack "=20!"
Right (" !","")
>>> qp_dec $ Data.ByteString.Char8.pack "=20=21"
Right (" !","")

A Left value is only ever returned on decoding errors.

>>> qp_dec $ Data.ByteString.Char8.pack "=2"
Right ("","=2")
>>> qp_dec $ Data.ByteString.Char8.pack "=2g"
Left ("","=2g")

Convenient function that calls qp_enc repeatedly until the whole input data is encoded.

A synonym for qp_dec.