TOML · The Julia Language
Description: Documentation for The Julia Language.

# TOML

TOML.jl is a Julia standard library for parsing and writing TOML v1.0 files.

## Parsing TOML data

    julia> using TOML

    julia> data = """
               [database]
               server = "192.168.1.1"
               ports = [ 8001, 8001, 8002 ]
           """;

    julia> TOML.parse(data)
    Dict{String, Any} with 1 entry:
      "database" => Dict{String, Any}("server"=>"192.168.1.1", "ports"=>[8001, 8001…

To parse a file, use `TOML.parsefile`. If the file has a syntax error, an exception is thrown:

    julia> using TOML

    julia> TOML.parse("""
               value = 0.0.0
           """)
    ERROR: TOML Parser error:
    none:1:16 error: failed to parse value
          value = 0.0.0
                     ^
    [...]

There are other versions of the parse functions (`TOML.tryparse` and `TOML.tryparsefile`) that instead of throwing exceptions on parser error returns a `TOML.ParserError` with information:

    julia> using TOML

    julia> err = TOML.tryparse("""
               value = 0.0.0
           """);

    julia> err.type
    ErrGenericValueError::ErrorType = 14

    julia> err.line
    1

    julia> err.column
    16

## Exporting data to TOML file

The `TOML.print` function is used to print (or serialize) data into TOML format.

    julia> using TOML

    julia> data = Dict(
              "names" => ["Julia", "Julio"],
              "age" => [10, 20],
           );

    julia> TOML.print(data)
    names = ["Julia", "Julio"]
    age = [10, 20]

    julia> fname = tempname();

    julia> open(fname, "w") do io
               TOML.print(io, data)
           end

    julia> TOML.parsefile(fname)
    Dict{String, Any} with 2 entries:
      "names" => ["Julia", "Julio"]
      "age"   => [10, 20]

Keys can be sorted according to some value

    julia> using TOML

    julia> TOML.print(Dict(
           "abc"  => 1,
           "ab"   => 2,
           "abcd" => 3,
           ); sorted=true, by=length)
    ab = 2
    abc = 1
    abcd = 3

For custom structs, pass a function that converts the struct to a supported type

    julia> using TOML

    julia> struct MyStruct
               a::Int
               b::String
           end

    julia> TOML.print(Dict("foo" => MyStruct(5, "bar"))) do x
               x isa MyStruct && return [x.a, x.b]
               error("unhandled type $(typeof(x))")
           end
    foo = [5, "bar"]

## References

`TOML.parse` — Function

    parse(x::Union{AbstractString, IO})
    parse(p::Parser, x::Union{AbstractString, IO})

Parse the string or stream `x`, and return the resulting table (dictionary). Throw a `ParserError` upon failure.

See also `TOML.tryparse`.

source
`TOML.parsefile` — Function

    parsefile(f::AbstractString)
    parsefile(p::Parser, f::AbstractString)

Parse file `f` and return the resulting table (dictionary). Throw a `ParserError` upon failure.

See also `TOML.tryparsefile`.

source
`TOML.tryparse` — Function

    tryparse(x::Union{AbstractString, IO})
    tryparse(p::Parser, x::Union{AbstractString, IO})

Parse the string or stream `x`, and return the resulting table (dictionary). Return a `ParserError` upon failure.

See also `TOML.parse`.

source
`TOML.tryparsefile` — Function

    tryparsefile(f::AbstractString)
    tryparsefile(p::Parser, f::AbstractString)

Parse file `f` and return the resulting table (dictionary). Return a `ParserError` upon failure.

See also `TOML.parsefile`.

source
`TOML.print` — Function

    print([to_toml::Function], io::IO [=stdout], data::AbstractDict; sorted=false, by=identity, inline_tables::IdSet{<:AbstractDict})

Write `data` as TOML syntax to the stream `io`. If the keyword argument `sorted` is set to `true`, sort tables according to the function given by the keyword argument `by`. If the keyword argument `inline_tables` is given, it should be a set of tables that should be printed "inline".

The following data types are supported: `AbstractDict`, `AbstractVector`, `AbstractString`, `Integer`, `AbstractFloat`, `Bool`, `Dates.DateTime`, `Dates.Time`, `Dates.Date`. Note that the integers and floats need to be convertible to `Float64` and `Int64` respectively. For other data types, pass the function `to_toml` that takes the data types and returns a value of a supported type.

source
`TOML.Parser` — Type

    Parser()

Constructor for a TOML `Parser`. Note that in most cases one does not need to explicitly create a `Parser` but instead one directly use use `TOML.parsefile` or `TOML.parse`. Using an explicit parser will however reuse some internal data structures which can be beneficial for performance if a larger number of small files are parsed.

source
`TOML.ParserError` — Type

    ParserError

Type that is returned from `tryparse` and `tryparsefile` when parsing fails. It contains (among others) the following fields:

- `pos`, the position in the string when the error happened
- `table`, the result that so far was successfully parsed
- `type`, an error type, different for different types of errors

source

Theme

This document was generated with Documenter.jl version 1.17.0 on Thursday 9 April 2026. Using Julia version 1.12.6.