mir-toml 0.1.1

a mir-ion (de)serialization frontend for TOML files

To use this package, run the following command in your project's root directory:

Manual usage
Put the following dependency into your project's dependences section:


As a believer of mir-ion as great general serialization framework for D, I have implemented TOML support for mir-ion.


import mir.toml;
import mir.serde;
import mir.algebraic;

import std.datetime.date;
import std.stdio;
import std.file : readText;

alias StringOrDouble = Algebraic!(string, double);

struct Person
    string name;
    Date dayOfBirth;

struct Database
    bool enabled;
    ushort[] ports;
    StringOrDouble[][] data;

struct MyDocument
    // NOTE: regular members MUST come before members that are serialized as
    // tables or arrays of tables. (structs and struct arrays)
    // Otherwise an exception is thrown at runtime
    string title;

    // represented as `owner = { ... }` instead of creating an `[owner]` section
    Person owner;

    Database database;

void main()
    MyDocument document = {
        title: "TOML Example",
        owner: Person(
            "Max Mustermann",
            Date(1979, 5, 27)
        database: Database(
            [8000, 8001, 8002],
                [StringOrDouble(1.4), StringOrDouble("cool")],

    writeln(serializeToml(document, TOMLBeautyConfig.full));

    /* output:
    title = "TOML Example"
    owner = { name = "Max Mustermann", dob = 1979-05-27 }

      enabled = true
      ports = [ 8000, 8001, 8002 ]
      data = [ [ 1.4, "cool" ], [], [ "ok" ] ]

    // parsing TOML:

See also: examples.d for tested examples.

Implementation notes


  • null values will either be omitted if possible or otherwise throw an exception at runtime
    • exception: typed empty array null is serialized as empty array
    • if you want to make optional fields, you should use Variant!(void, T) as type instead of Nullable.
  • mixing structs (tables) and other values in arrays will throw an exception at runtime if tables don't come first
    • to fix this, annotate with @tomlInlineArray or change type to TomlInlineArray!(T[])
  • string types can be enforced using @tomlLiteralString ('string'), @tomlMultilineString ("""string""") or @tomlMultilineLiteralString ('''string''') - however note that runtime exceptions may occur if they are not representable
  • putting regular fields of a struct after table fields (struct members) will break at runtime
    • planned to be fixed, to support conversion between formats, but for now not supported
    • for serialization of D datatypes you can simply move your fields around to have the proper output, but you can't enforce this e.g. for parsed JSON


  • based on the toml library, which doesn't keep ordering of maps
  • only deserializes values, does not keep track of aesthetic things like which tables were inlined, how numbers and strings are serialized
    • might want to somehow support this with annotations in the future
  • webfreak
mir-ion, toml
0.1.1 2022-Nov-30
0.1.0 2022-Nov-30
0.0.1 2022-Nov-29
~master 2022-Nov-30
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