TOML

TOML is a file format for configuration files. It is intended to be easy to read and write due to obvious semantics which aim to be "minimal", and is designed to map unambiguously to a dictionary. Its specification is open-source, and receives community contributions. TOML is used in a number of software projects, and is implemented in many programming languages. The name "TOML" is an acronym for "Tom's Obvious, Minimal Language" referring to its creator, Tom Preston-Werner.

Syntax

TOML's syntax primarily consists of key = value pairs, ection names/code>, and # (for comments). TOML's syntax somewhat resembles that of . INI files, but it includes a formal specification,
whereas the INI file format suffers from many competing variants.

Its specification includes a list of supported data types: String, Integer, Float, Boolean, Datetime, Array, and Table.

Example

# This is a TOML document.

title = "TOML Example"

wnername = "Tom Preston-Werner"
dob = 1979-05-27T07:32:00-08:00 # First class dates

atabaseserver = "192.168.1.1"
ports = 8000, 8001, 8002 connection_max = 5000
enabled = true

ervers
# Indentation (tabs and/or spaces) is allowed but not required
ervers.alpha ip = "10.0.0.1"
dc = "eqdc10"

ervers.beta ip = "10.0.0.2"
dc = "eqdc10"

lientsdata = ["gamma",_"delta"_[1,_2.html" ;"title="gamma",_"delta".html" ;"title="["gamma", "delta"">["gamma", "delta" [1, 2">gamma",_"delta".html" ;"title="["gamma", "delta"">["gamma", "delta" [1, 2]

# Line breaks are OK when inside arrays
hosts = [
"alpha",
"omega"
]

Use cases

TOML is used in a variety of settings (some related to its creator), such as:
* Static site generators like Jekyll and Hugo
* Continuous integration on e.g. GitHub and GitLab

Python
programming language


programming language

Comparison to other formats

The following table draws on th
TOML specification
to make a comparison to other popular configuration formats.

Criticism

Since its first release TOML has received several critiques. The following is not a consensus. The HitchDev lists the following points as problematic in TOML:

* TOML is verbose; it is not DRY and it is syntactically noisy
* TOML's hierarchies are difficult to infer from syntax alone
* Overcomplication: Like YAML, TOML has too many features
* In TOML the syntax determines the data types ("syntax typing")

Th
libconfini
project has since released a more extensive critique of TOML from the INI perspective, listing the following points (among others) as problematic:

* TOML lets the configuration file decide about data types (syntax typing), when ''de facto'' it is the client application that decides. Any mismatching type will be either ignored or converted to the expected type (depending on the parser) anyway
* TOML re-introduces what human-friendly languages normally try to get rid of: a verbose syntax and the necessity of using quotes for strings
* TOML syntax is always case-sensitive, despite the fact that there are situations where configuration files ''must'' be case-insensitive (as, for instance, configuration files that map a FAT32 filesystem or HTML tags)
* TOML uses square brackets for arrays even though square brackets are already reserved for table names; furthermore any special syntax for arrays brings the language back to syntax typing
* A TOML table must be populated in a single step; merging multiple TOML files is problematic
* TOML arbitrarily introduces a syntax for dates
* TOML allows (but discourages) the empty string as a key
* TOML's quoting rules introduce confusion between actual strings (free content) and enumeration labels (i.e. choices within closed sets of options)
* TOML's rules cannot be inferred from the content, therefore editing a TOML file requires prior knowledge of the language
* TOML is backward-incompatible with INI

See also

* INI file
* JSON - from JavaScript ecosystem
* Recfiles
* YAML
* HOCON

References

External links

*
*

{{Data Exchange

Computer file formats
Configuration files
Lightweight markup languages
Markup languages