Hex

Hex is a small package for working with elm/bytes. It exposes two functions.

• fromBytes : Bytes -> String
• toBytes : String -> Maybe Bytes

The first function gives a hexadecimal representation of a Bytes, value, e.g., something like "6A45F2". The second takes a string like the one just given and returns a value of type Maybe Bytes. Such a function call can fail, e.g., on an input "6A45F!".

Examples

Hex.toBytes "FF66" |> Maybe.map Hex.fromBytes == Just "FF66"

$ elm repl
> import Hex exposing(..)
> import Bytes.Encode as Encode exposing(encode)

> encode (Encode.string "Hello") |> Hex.fromBytes
"48656C6C6F" : String

> Hex.toBytes "FF66" |> Maybe.map Hex.fromBytes
Just "FF66" : Maybe String

> Hex.toBytes "FF66!!" |> Maybe.map Hex.fromBytes
Nothing : Maybe String

Notes

The function Hex.toBytes is case-insensitive

 > Hex.toBytes "ff66" |> Maybe.map Hex.fromBytes
Just "FF66"

If you prefer lower-case output from Hex.fromBytes, you can do as in this example:

> Hex.toBytes "ff66" |> Maybe.map Hex.fromBytes |> Maybe.map String.toLower
Just "ff66" : Maybe String