Crockford's base32 encoding in Elm

Encode integers as Crockford-style base32 strings.

From the specification:

Base 32 is a textual 32-symbol notation for expressing numbers in a form that can be conveniently and accurately transmitted between humans and computer systems. It can be used for out of band communication of public keys.

The encoding scheme is required to

  • Be human readable and machine readable.
  • Be compact. Humans have difficulty in manipulating long strings of arbitrary symbols.
  • Be error resistant. Entering the symbols must not require keyboarding gymnastics.
  • Be pronounceable. Humans should be able to accurately transmit the symbols to other humans using a telephone.

This package provides functions for encoding and decoding base32 data.

Examples

-- Encodes a non-negative integer as a base32 string according to Crockford's encoding scheme.
Crockford.encode 1337 --> Ok "19S" : Result Crockford.Error String

-- Decodes a base32 string into a non-negative integer.
Crockford.decode "19S" --> Ok 1337 : Result Crockford.Error Int

-- Negative integers cannot be encoded.
Crockford.encode -1 --> Err NegativeNumberError : Result Crockford.Error String

It's also possible to have a checksum number appended to the string when encoded. This checksum number will be used to validate the correctness of the encoded number when decoding.

Crockford.encodeWithChecksum 32 --> Ok "10*" : Result Crockford.Error String

Crockford.decodeWithChecksum "10*" --> Ok 32 : Result Crockford.Error Int

Crockford.decodeWithChecksum "10~" --> Err Crockford.InvalidChecksum : Result Crockford.Error Int