This is a TOML v1.0.0 parser library, with dates supporting nanosecond precision. It passes all tests in toml-test v1.3.0. Click the "TOML Compliance" badge for logs of toml-test.

This code is a fork of Greg Hendershott's TOML parser. Unlike that repository, this version is available on pkgs.racket-lang.org and includes support for generating TOML.

raco pkg install --auto toml

(require toml)
(parse-toml s) ;; where `s` is a `string?`

Sample output of a program such as

#lang racket
(require toml)
(define sample-expr
  '#hasheq((table . #hasheq((key . 5)
                            (array . (#hasheq((a . 1) (b . 2))
                                      #hasheq((a . 2) (b . 4))))))
           (|another-table| . #hasheq((key . 10)))))
(display (tomlexpr->string sample-expr))

would be

[another-table]
key = 10
[table]
key = 5
[[table.array]]
a = 1
b = 2
[[table.array]]
a = 2
b = 4

• Remain current with the most recent TOML release version.

• Provide useful error messages with positions (line:col:ofs). Do so for both syntax errors and semantic errors (such as table conflicts).

• Return a Racket hasheq that satisfies the json library's jsexpr? predicate, so that you can run it through jsexpr->string to produce a JSON string.

  Caveat: Any TOML datetime values are date structs, which won't satisfy jsexpr?. Originally I parsed these to a current-seconds-style integer value. But toml-tests needs things to be tagged with types, so that's why I had to switch. I should probably provide a conversion function to turn any such instances back into a datetime string so that it can be passed to jsexpr->string.