Base64 Encoding in Haskell

Here’s the translation of the Base64 Encoding example from Go to Haskell, formatted in Markdown suitable for Hugo:

import qualified Data.ByteString.Base64 as B64
import qualified Data.ByteString.Char8 as C8

main :: IO ()
main = do
    -- Here's the string we'll encode/decode.
    let data = "abc123!?$*&()'-=@~"

    -- Haskell provides base64 encoding/decoding through the base64-bytestring package.
    -- Here's how to encode using the standard encoder.
    let sEnc = B64.encode $ C8.pack data
    putStrLn $ C8.unpack sEnc

    -- Decoding may return an error, which you can handle with Either.
    case B64.decode sEnc of
        Left err -> putStrLn $ "Decoding error: " ++ err
        Right sDec -> putStrLn $ C8.unpack sDec

    putStrLn ""

    -- This encodes/decodes using a URL-compatible base64 format.
    let uEnc = B64.encodeUrlSafe $ C8.pack data
    putStrLn $ C8.unpack uEnc

    case B64.decodeUrlSafe uEnc of
        Left err -> putStrLn $ "Decoding error: " ++ err
        Right uDec -> putStrLn $ C8.unpack uDec

Haskell provides support for base64 encoding/decoding through the base64-bytestring package. This example demonstrates how to use it.

First, we import the necessary modules: Data.ByteString.Base64 for base64 operations and Data.ByteString.Char8 for working with ByteStrings.

In the main function, we define our sample string data.

For standard base64 encoding:

1. We use B64.encode to encode the ByteString version of our data.
2. We print the encoded string after converting it back to a regular String.

For decoding:

1. We use B64.decode which returns an Either type.
2. We handle both success and error cases using pattern matching.

The process is similar for URL-safe base64 encoding/decoding, but we use B64.encodeUrlSafe and B64.decodeUrlSafe instead.

Note that in Haskell, we’re working with ByteStrings instead of the []byte type used in the original example. This is idiomatic for Haskell when dealing with binary data or text that needs to be processed efficiently.

To run this program:

$ runhaskell base64_encoding.hs
YWJjMTIzIT8kKiYoKSctPUB+
abc123!?$*&()'-=@~

YWJjMTIzIT8kKiYoKSctPUB-
abc123!?$*&()'-=@~

The string encodes to slightly different values with the standard and URL base64 encoders (trailing + vs -) but they both decode to the original string as desired.