base64-0.4.2: Fast RFC 4648-compliant Base64 encoding

Copyright(c) 2019-2020 Emily Pillmore
MaintainerEmily Pillmore <>
Safe HaskellNone



This module contains the combinators implementing the RFC 4648 specification for the Base64 encoding including unpadded and lenient variants



encodeBase64 :: Text -> Text Source #

Encode a Text value in Base64 with padding.

See: RFC-4648 section 4

decodeBase64 :: Text -> Either Text Text Source #

Decode a padded Base64-encoded Text value

See: RFC-4648 section 4

Note: This function makes sure that decoding is total by deferring to decodeLatin1. This will always round trip for any valid Base64-encoded text value, but it may not round trip for bad inputs. The onus is on the caller to make sure inputs are valid. If unsure, defer to decodeBase64With and pass in a custom decode function.

decodeBase64With Source #


:: (ByteString -> Either err Text)

convert a bytestring to text (e.g. decodeUtf8')

-> ByteString

Input text to decode

-> Either (Base64Error err) Text 

Attempt to decode a ByteString value as Base64, converting from ByteString to Text according to some encoding function. In practice, This is something like decodeUtf8', which may produce an error.

See: RFC-4648 section 4


decodeBase64With decodeUtf8'
  :: ByteString -> Either (Base64Error UnicodeException) Text

decodeBase64Lenient :: Text -> Text Source #

Leniently decode a Base64-encoded Text value. This function will not generate parse errors. If input data contains padding chars, then the input will be parsed up until the first pad character.

Note: This is not RFC 4648-compliant.

isBase64 :: Text -> Bool Source #

Tell whether a Text value is Base64-encoded.

isValidBase64 :: Text -> Bool Source #

Tell whether a Text value is a valid Base64 format.

This will not tell you whether or not this is a correct Base64 representation, only that it conforms to the correct shape. To check whether it is a true Base64 encoded Text value, use isBase64.