elm-tiny-inflate

Decompress deflate compressed data. Deflate compression is used in the zip and gzip archive formats, but also as a building block in other file formats like png and woff. The package supports raw inflate, zlib, and gzip.

import Bytes exposing (Bytes, Endianness(..))
import Bytes.Decode as Decode
import Bytes.Encode as Encode
import Inflate

{-| Some sample text
-}
text : String
text =
    "Myn geast ferdizet"

{-| The `text` compressed with raw deflate

The bytes are combined into 32bit integers using
hex notation so they are shorter in the docs

-}
textCompressedBytes =
    [ 0xF3ADCC53
    , 0x484F4D2C
    , 0x2E51484B
    , 0x2D4AC9AC
    , 0x4A2D0100
    ]
        |> List.map (Encode.unsignedInt32 BE)
        |> Encode.sequence
        |> Encode.encode

decodeString : Bytes -> Maybe String
decodeString buffer =
    let
        decoder =
            Decode.string (Encode.getStringWidth text)
    in
    Decode.decode decoder buffer

decompressed =
    textCompressedBytes
        |> Inflate.inflate
        |> Maybe.andThen decodeString
        |> Maybe.withDefault ""

Here the deflated data is given as a list of bytes, in practice you would probably load the Bytes directly. The inflation is only a small step in the process: I've included the full decoding of the compressed string to show what that looks like.

Thanks

• Jørgen Ibsen, author of tinf which this package is based on
• Devon Govett, author of tiny-inflate, a JS port of tinf (easier to read)