M. Tuddenham
                                                                   August 2023

                                   UDSV SerDe

1. Introduction

  This is a rust serde library for the UNIX Delimiter Separated Values (UDSV)
  file format.

2. Records vs File

  `record_to_str`, and `record_from_str` handle just one record. In the future
  there will be `to_str` and `from_str` to handle a whole file of records.

3. Non-specified data types

  While Numbers/Enums/Structs/Tuples aren't in the original specification, an
  attempt has been made to best (de)serialise them here.

3.1 Numbers

  To do.

3.2 Enums
  Enums are always externally tagged.

3.3 Struct
  Structs are flattened, and the fields are colon-separated. Structs are never
  tagged.

3.4 Tuples

  Tuples are (de)serialised identically to lists.

3.5 Options

  `None` is serialised as the empty string, `Some(x)` is just `x` serialised.
  Options are lossy, i.e. there is no distinction between `Some(())`,
  `Some("")`, and `None`.

3.6 Booleans

  Booleans are serialised as the strings "true" and "false".

4. To do list

  - Allow (de)serialising many records e.g. from a file.
  - Add tracing to tests https://docs.rs/tracing-test/latest/tracing_test/
  - Better errors - provide additional information in its error type, for
    example the line and column at which the error occurred, the byte offset into
    the input, or the current key being processed.
  - Ser
    - Disallow nesting
  - De
    - Allow derseriliasing into a &str - https://serde.rs/lifetimes.html
    - Disallow nesting
    - floats
    - signed ints
    - int/float overflow