toml 6.0.0 · OCaml Package

Partial lenses (returns option) for accessing TOML structures. They make it possible to read/write deeply nested immutable values.

type ('a, 'b) lens = {

get : 'a -> 'b option;
set : 'b -> 'a -> 'a option;

}

val get : 'a -> ('a, 'b) lens -> 'b option

Extracts a value from some Toml data using a lens. Returns Some value if the underlying data matched the lens, or None.

Example:

utop # let toml_data = Toml.Parser.(from_string "
[this.is.a.deeply.nested.table]
answer=42" |> unsafe);;
val toml_data : Types.table = <abstr>

utop # TomlLenses.(get toml_data (
  key "this" |-- table
  |-- key "is" |-- table
  |-- key "a" |-- table
  |-- key "deeply" |-- table
  |-- key "nested" |-- table
  |-- key "table" |-- table
  |-- key "answer"|-- int ));;
- : int option = Some 42

since 4.0.0

val set : 'b -> 'a -> ('a, 'b) lens -> 'a option

Replaces an existing value in some Toml data using a lens. Returns Some value if the underlying data matched the lens, or None.

Example:

utop # let toml_data = Toml.Parser.(from_string "
[this.is.a.deeply.nested.table]
answer=42" |> unsafe);;
val toml_data : Types.table = <abstr>

utop # let maybe_toml_data' = TomlLenses.(set 2015 toml_data (
  key "this" |-- table
  |-- key "is" |-- table
  |-- key "a" |-- table
  |-- key "deeply" |-- table
  |-- key "nested" |-- table
  |-- key "table" |-- table
  |-- key "answer"|-- int ));;
val maybe_toml_data' : Types.table option = Some <abstr>

utop # let (Some toml_data') = maybe_toml_data';;
val toml_data' : Types.table = <abstr>

utop # Toml.Printer.string_of_table toml_data';;
- : bytes = "[this.is.a.deeply.nested.table]\nanswer = 2015\n"

since 4.0.0

val update : ('b -> 'b option) -> 'a -> ('a, 'b) lens -> 'a option

Applies a function on an existing value in some Toml data. Returns Some value if the underlying data matched the lens, or None.

Example:

utop # let toml_data = Toml.Parser.(from_string "
  [[table.of.mixed_values]]
  int=0
  str=\"a\"
  [[table.of.mixed_values]]
  str=\"b\"
  [[table.of.mixed_values]]
  int=3
" |> unsafe);;
val toml_data : Types.table = <abstr>

utop # let maybe_toml_data' =  TomlLenses.(update
  (fun ts -> Some (
    List.map (fun t ->
      (** Add 'int=42' to each table which doesn't already have an 'int' key *)
      if not (Types.Table.mem (Toml.key "int") t) then
        Types.Table.add (Toml.key "int") (Types.TInt 42) t
      else t) ts))
  toml_data
  (key "table" |-- table
   |-- key "of" |-- table
   |-- key "mixed_values" |-- array |-- tables));;
val maybe_toml_data' : Types.table option = Some <abstr>

utop # let (Some toml_data') = maybe_toml_data';;
val toml_data' : Types.table = <abstr>

utop # print_endline @@ Toml.Printer.string_of_table toml_data';;

[[table.of.mixed_values]]
int = 0
str = "a"
[[table.of.mixed_values]]
int = 42
str = "b"
[[table.of.mixed_values]]
int = 3
- : unit = ()

since 4.0.0

val compose : ('a, 'b) lens -> ('c, 'a) lens -> ('c, 'b) lens

Lens composition.

since 4.0.0

val (|--) : ('a, 'b) lens -> ('b, 'c) lens -> ('a, 'c) lens

Flipped lens composition.

since 4.0.0

val key : string -> (Types.table, Types.value) lens

Lens to a particular value in a table.

raises Types.Table.Key.Bad_key
if the key contains invalid characters.

since 4.0.0

val field : string -> (Types.table, Types.table) lens

Combines the key and table lenses, for the common case of nested tables.

raises Types.Table.Key.Bad_key
if the key contains invalid characters.

since 4.0.0

val string : (Types.value, string) lens

Lens to a string value.

since 4.0.0

val bool : (Types.value, bool) lens

Lens to a boolean value.

since 4.0.0

val int : (Types.value, int) lens

Lens to an int value.

since 4.0.0

val float : (Types.value, float) lens

Lens to a float value.

since 4.0.0

val date : (Types.value, float) lens

Lens to a date value.

since 4.0.0

val array : (Types.value, Types.array) lens

Lens to an array value.

since 4.0.0

val table : (Types.value, Types.table) lens

Lens to a table value.

since 4.0.0

val strings : (Types.array, string list) lens

Lens to an array of strings.

since 4.0.0

val bools : (Types.array, bool list) lens

Lens to an array of booleans.

since 4.0.0

val ints : (Types.array, int list) lens

Lens to an array of ints.

since 4.0.0

val floats : (Types.array, float list) lens

Lens to an array of floats.

since 4.0.0

val dates : (Types.array, float list) lens

Lens to an array of dates.

since 4.0.0

val tables : (Types.array, Types.table list) lens

Lens to an array of tables.

since 4.0.0

val arrays : (Types.array, Types.array list) lens

Lens to an array of arrays.

since 4.0.0

package toml