guile-toml/README.org

* guile-toml

TOML for Guile; v1.0.0 compliant.

** Installation

For now: add this folder to your ~GUILE_LOAD_PATH~.

** Usage

When parsing and building TOML documents, guile-toml follows [[https://github.com/aconchillo/guile-json][guile-json]] as close as possible. TOML types correspond to Guile types according to the following table:

| TOML           | Guile               |
|----------------+---------------------|
| string         | string [0]          |
| key-value pair | alist               |
| array          | vector              |
| integer/float  | real                |
| true           | #t                  |
| false          | #f                  |
| datetime       | SRFI-19 date [1]    |
| nan            | +nan.0              |
| ±inf           | ±inf.0              |

To start using guile-toml:
#+begin_src scheme
(use-modules (toml))
#+end_src

[0]: TOML's default behaviour for invalid UTF-8 is to fail, whereas [[https://www.gnu.org/software/guile/manual/html_node/Encoding.html][Guile's default behavior]] is to replace invalid UTF-8 with the replacement character <20>. If you prefer TOML's behavior, use ~(set-port-conversion-strategy! (current-input-port) 'error)~.

[1]: TOML's ~time-local~ is parsed same as a ~datetime-local~ on the date of ~1970-01-01~.

*** Reading TOML documents

- ~(toml->scm str)~

  Reads a TOML document from the given string. Guile-toml's parsing is implemented with ~(ice-9 peg)~, which unfortunately does not support ports. See below for how to use this with a TOML file.

*** Building TOML documents
- ~(scm->toml native #:optional port)~

  Creates a TOML document from the given native Guile value. The TOML document is written into the given port, or to the current output port if none is given.

** Examples
- Basic ~toml->scm~ usage:
#+begin_src scheme
> (toml->scm "[a]\n b.c = \"hi world\"")

(("a" ("b" ("c" . "hi world"))))
#+end_src

- Read a TOML file and parse it (example from [[https://toml.io][toml.io]]):
#+begin_src scheme
> (use-modules (toml) (ice-9 textual-ports))
> (toml->scm (call-with-input-file "example.toml" get-string-all))

(("servers"
  ("beta" ("role" . "backend") ("ip" . "10.0.0.2"))
  ("alpha"
   ("role" . "frontend")
   ("ip" . "10.0.0.1")))
 ("database"
  ("temp_targets" ("case" . 72.0) ("cpu" . 79.5))
  ("data" . #(#("delta" "phi") #(3.14)))
  ("ports" . #(8000 8001 8002))
  ("enabled" . #t))
 ("owner"
  ("dob"
   .
   #<date nanosecond: 0 second: 0 minute: 32 hour: 7 day: 27 month: 5 year: 1979 zone-offset: -28800>)
  ("name" . "Tom Preston-Werner"))
 ("title" . "TOML Example"))
 #+end_src

~example.toml~:
#+begin_src toml
# This is a TOML document

title = "TOML Example"

[owner]
name = "Tom Preston-Werner"
dob = 1979-05-27T07:32:00-08:00

[database]
enabled = true
ports = [ 8000, 8001, 8002 ]
data = [ ["delta", "phi"], [3.14] ]
temp_targets = { cpu = 79.5, case = 72.0 }

[servers]

[servers.alpha]
ip = "10.0.0.1"
role = "frontend"

[servers.beta]
ip = "10.0.0.2"
role = "backend"
#+end_src