-module(on).
-compile([no_auto_import, nowarn_unused_vars, nowarn_unused_function, nowarn_nomatch]).
-define(FILEPATH, "src/on.gleam").
-export([ok/2, error/2, error_ok/3, ok_error/3, true/2, false/2, false_true/3, lazy_false_true/3, true_false/3, lazy_true_false/3, some/2, none/2, none_some/3, lazy_none_some/3, some_none/3, nonempty/2, empty/2, empty_nonempty/3, lazy_empty_nonempty/3, nonempty_empty/3, empty_singleton_gt1/4, lazy_empty_singleton_gt1/4, empty_gt1_singleton/4, lazy_empty_gt1_singleton/4, singleton_gt1_empty/4, main/0]).

-if(?OTP_RELEASE >= 27).
-define(MODULEDOC(Str), -moduledoc(Str)).
-define(DOC(Str), -doc(Str)).
-else.
-define(MODULEDOC(Str), -compile([])).
-define(DOC(Str), -compile([])).
-endif.

-file("src/on.gleam", 29).
?DOC(
    " Given a Result(a, b) and a callback f(a) -> Result(c, b) applies\n"
    " the callback if the Result has type Ok else maps the Error variant\n"
    " of type Result(a, b) to the Error variant of type Result(c, b).\n"
    " \n"
    " Equivalent to result.try and to error_ok(_, fn(e) -> {Error(e)}, _).\n"
    "\n"
    " ### Example 1\n"
    "\n"
    " ```gleam\n"
    " use ok_payload <- on.ok(Ok(3))\n"
    " // -> execution proceeds, ok_payload == 3; the current scope must\n"
    " // return a Result(c, b) for some c, b\n"
    " ```\n"
    "\n"
    " ### Example 2\n"
    "\n"
    " ```gleam\n"
    " use ok_payload <- on.ok(Error(\"Joe\"))\n"
    " // -> execution discontinues, scope returns Error(\"Joe\")\n"
    " ```\n"
).
-spec ok({ok, DTU} | {error, DTV}, fun((DTU) -> {ok, DTY} | {error, DTV})) -> {ok,
        DTY} |
    {error, DTV}.
ok(Result, F2) ->
    case Result of
        {error, E} ->
            {error, E};

        {ok, A} ->
            F2(A)
    end.

-file("src/on.gleam", 60).
?DOC(
    " Given a Result(a, b) and a callback f(b) -> Result(a, c) applies\n"
    " the callback if the Result has type Error else maps the Ok variant\n"
    " of type Result(a, b) to the Ok variant of type Result(c, b).\n"
    "\n"
    " Equivalent to on.ok_error(_, fn(o) -> {Ok(o)}, _).\n"
    "\n"
    " ### Example 1\n"
    "\n"
    " ```gleam\n"
    " use error_payload <- on.error(Ok(3))\n"
    " // -> execution discontinues, scope returns Ok(3)\n"
    " ```\n"
    "\n"
    " ### Example 2\n"
    "\n"
    " ```gleam\n"
    " use error_payload <- on.error(Error(\"Joe\"))\n"
    " // -> execution proceeds, error_payload == \"Joe\";\n"
    " // the scope must return a Result(a, c)\n"
    " ```\n"
).
-spec error({ok, DUD} | {error, DUE}, fun((DUE) -> {ok, DUD} | {error, DUH})) -> {ok,
        DUD} |
    {error, DUH}.
error(Result, F2) ->
    case Result of
        {ok, A} ->
            {ok, A};

        {error, E} ->
            F2(E)
    end.

-file("src/on.gleam", 99).
?DOC(
    " Given a Result(a, b) and callbacks f(b) -> c, f(a) -> c, \n"
    " returns the evaluation of the relevant callback depending on\n"
    " the contents of the Result.\n"
    "\n"
    " ### Example 1\n"
    " \n"
    " ```gleam\n"
    " use ok_payload <- on.error_ok(\n"
    "   Ok(3),\n"
    "   on_error: fn(e) { \"hi \" <> e <> \"!\" },\n"
    " )\n"
    " // -> execution proceeds, ok_payload == 3; the scope must return\n"
    " // a String to match the return value of the on_error callback\n"
    " ```\n"
    " \n"
    " ### Example 2\n"
    " \n"
    " ```gleam\n"
    " use ok_payload <- on.error_ok(\n"
    "   Error(\"Joe\"),\n"
    "   on_error: fn(e) { \"hi \" <> e <> \"!\" },\n"
    " )\n"
    " // -> execution discontinues, scope returns \"hi Joe!\"\n"
    " ```\n"
).
-spec error_ok({ok, DUM} | {error, DUN}, fun((DUN) -> DUQ), fun((DUM) -> DUQ)) -> DUQ.
error_ok(Result, F1, F2) ->
    case Result of
        {error, B} ->
            F1(B);

        {ok, A} ->
            F2(A)
    end.

-file("src/on.gleam", 136).
?DOC(
    " Given a Result(a, b) and callbacks f(a) -> c, f(b) -> c,\n"
    " returns the evaluation of the relevant callback depending on\n"
    " the contents of the Result.\n"
    "\n"
    " ### Example 1\n"
    "\n"
    " ```gleam\n"
    " use error_payload <- on.ok_error(\n"
    "   Ok(3),\n"
    "   on_ok: fn(x) { x + 1 },\n"
    " )\n"
    " // -> execution discontinues, scope returns 4\n"
    " ```\n"
    "\n"
    " ### Example 2\n"
    " \n"
    " ```gleam\n"
    " use error_payload <- on.ok_error(\n"
    "   Error(\"Joe\"),\n"
    "   on_ok: fn(x) { x + 1 },\n"
    " )\n"
    " // -> execution proceeds, error_payload == \"Joe\"; the scope\n"
    " // must return an Int to match the return value of the on_ok\n"
    " // callback\n"
    " ```\n"
).
-spec ok_error({ok, DUR} | {error, DUS}, fun((DUR) -> DUV), fun((DUS) -> DUV)) -> DUV.
ok_error(Result, F1, F2) ->
    case Result of
        {ok, A} ->
            F1(A);

        {error, B} ->
            F2(B)
    end.

-file("src/on.gleam", 170).
?DOC(
    " Given a Bool returns False if the bool is False, else\n"
    " returns a lazily evaluated callback.\n"
    "\n"
    " Equivalent to on.false_true(_, False, _).\n"
    "\n"
    " ### Example 1\n"
    "\n"
    " ```gleam\n"
    " use <- on.true(True)\n"
    " // -> execution proceeds, scope must return a Bool\n"
    " ```\n"
    "\n"
    " ### Example 2\n"
    "\n"
    " ```gleam\n"
    " use <- on.true(False)\n"
    " // -> execution discontinues, scope returns False\n"
    " ```\n"
).
-spec true(boolean(), fun(() -> boolean())) -> boolean().
true(Bool, F2) ->
    case Bool of
        false ->
            false;

        true ->
            F2()
    end.

-file("src/on.gleam", 197).
?DOC(
    " Given a Bool returns True if the bool is True, else\n"
    " returns a lazily evaluated callback.\n"
    "\n"
    " ### Example 1\n"
    "\n"
    " ```gleam\n"
    " use <- on.false(True)\n"
    " // -> execution discontinues, scope returns True\n"
    " ```\n"
    "\n"
    " ### Example 2\n"
    "\n"
    " ```gleam\n"
    " use <- on.false(False)\n"
    " // -> execution proceeds, scope must return a Bool\n"
    " ```\n"
).
-spec false(boolean(), fun(() -> boolean())) -> boolean().
false(Bool, F2) ->
    case Bool of
        true ->
            true;

        false ->
            F2()
    end.

-file("src/on.gleam", 236).
?DOC(
    " Given a Bool, a value of type c and a callback f() -> c,\n"
    " returns the value of type c if the bool is False, else the\n"
    " evaluation of the callback.\n"
    "\n"
    " ### Example 1\n"
    "\n"
    " ```gleam\n"
    " use <- on.false_true(\n"
    "   True,\n"
    "   on_false: \"Joe\",\n"
    " )\n"
    " // -> execution proceeds, the scope must return a String to \n"
    " // match the return value of the on_false argument\n"
    " ```\n"
    "\n"
    " ### Example 2\n"
    "\n"
    " ```gleam\n"
    " use <- on.false_true(\n"
    "   False,\n"
    "   on_false: \"Joe\",\n"
    " )\n"
    " // -> execution discontinues, scope returns \"Joe\"\n"
    " ```\n"
).
-spec false_true(boolean(), DUW, fun(() -> DUW)) -> DUW.
false_true(Bool, C, F2) ->
    case Bool of
        false ->
            C;

        true ->
            F2()
    end.

-file("src/on.gleam", 272).
?DOC(
    " Given a Bool and two callbacks f() -> c returns the\n"
    " evaluation of the first callback if the bool is False,\n"
    " else the second callback.\n"
    "\n"
    " ### Example 1\n"
    "\n"
    " ```gleam\n"
    " use <- on.lazy_false_true(\n"
    "   True,\n"
    "   on_false: fn() { \"Joe\" },\n"
    " )\n"
    " // -> execution proceeds, the scope must return a String \n"
    " // to match the return value of the on_false argument\n"
    " ```\n"
    "\n"
    " ### Example 2\n"
    "\n"
    " ```gleam\n"
    " use <- on.lazy_false_true(\n"
    "   False,\n"
    "   on_false: fn() { \"Joe\" },\n"
    " )\n"
    " // -> execution discontinues, scope returns \"Joe\"\n"
    " ```\n"
).
-spec lazy_false_true(boolean(), fun(() -> DUX), fun(() -> DUX)) -> DUX.
lazy_false_true(Bool, F1, F2) ->
    case Bool of
        false ->
            F1();

        true ->
            F2()
    end.

-file("src/on.gleam", 308).
?DOC(
    " Given a Bool, a value of type c and a callback f() -> c, \n"
    " returns the value of type c if the bool is True, else the\n"
    " evaluation of the callback.\n"
    "\n"
    " ### Example 1\n"
    "\n"
    " ```gleam\n"
    " use <- on.true_false(\n"
    "   True,\n"
    "   on_true: \"Joe\",\n"
    " )\n"
    " // -> execution discontinues, scope returns \"Joe\"\n"
    " ```\n"
    "\n"
    " ### Example 2\n"
    " \n"
    " ```gleam\n"
    " use <- on.true_false(\n"
    "   False,\n"
    "   on_true: \"Joe\",\n"
    " )\n"
    " // -> execution proceeds, the scope must return a String to \n"
    " // match the return value of the on_true argument\n"
    " ```\n"
).
-spec true_false(boolean(), DUY, fun(() -> DUY)) -> DUY.
true_false(Bool, C, F2) ->
    case Bool of
        true ->
            C;

        false ->
            F2()
    end.

-file("src/on.gleam", 345).
?DOC(
    " Given a Bool and two callbacks f() -> c returns the\n"
    " evaluation of the first callback if the bool is True,\n"
    " else the second callback.\n"
    "\n"
    "\n"
    " ### Example 1\n"
    "\n"
    " ```gleam\n"
    " use <- on.lazy_true_false(\n"
    "   True,\n"
    "   on_true: fn() { \"Joe\" },\n"
    " )\n"
    " // -> execution discontinues, scope returns \"Joe\"\n"
    " ```\n"
    "\n"
    " ### Example 2\n"
    "\n"
    " ```gleam\n"
    " use <- on.lazy_true_false(\n"
    "   False,\n"
    "   on_true: fn() { \"Joe\" },\n"
    " )\n"
    " // -> execution proceeds, the scope must return a String to \n"
    " // match the return value of the on_false argument\n"
    " ```\n"
).
-spec lazy_true_false(boolean(), fun(() -> DUZ), fun(() -> DUZ)) -> DUZ.
lazy_true_false(Bool, F1, F2) ->
    case Bool of
        true ->
            F1();

        false ->
            F2()
    end.

-file("src/on.gleam", 383).
?DOC(
    " Given an Option(a) and a callback f(a) -> Option(c)\n"
    " applies the callback to the payload a if the option is Some(a),\n"
    " else returns None.\n"
    "\n"
    " Equivalent to:\n"
    " - on.none_some(_, None, _).\n"
    " - option.then\n"
    " \n"
    " ### Example 1\n"
    "\n"
    " ```gleam\n"
    " use payload <- on.some(Some(3))\n"
    " // -> execution proceeds, payload == 3; the scope must return\n"
    " // an Option(c)\n"
    " ```\n"
    "\n"
    " ### Example 2\n"
    " \n"
    " ```gleam\n"
    " use payload <- on.some(None)\n"
    " // -> execution discontinues, scope returns None\n"
    " ```\n"
).
-spec some(gleam@option:option(DVA), fun((DVA) -> gleam@option:option(DVC))) -> gleam@option:option(DVC).
some(Option, F2) ->
    case Option of
        none ->
            none;

        {some, A} ->
            F2(A)
    end.

-file("src/on.gleam", 411).
?DOC(
    " Given an Option(a) and a callback f() -> Option(a), applies\n"
    " the callback if the option is None, else returns the option\n"
    " unchanged.\n"
    "\n"
    " ### Example 1\n"
    "\n"
    " ```gleam\n"
    " use <- on.none(Some(3))\n"
    " // -> execution discontinues, scope returns Some(3)\n"
    " ```\n"
    "\n"
    " ### Example 2\n"
    "\n"
    " ```gleam\n"
    " use <- on.none(None)\n"
    " // -> execution proceeds, the scope must return an Option(a)\n"
    " ```\n"
).
-spec none(gleam@option:option(DVF), fun(() -> gleam@option:option(DVF))) -> gleam@option:option(DVF).
none(Option, F2) ->
    case Option of
        {some, A} ->
            {some, A};

        none ->
            F2()
    end.

-file("src/on.gleam", 448).
?DOC(
    " Given an Option(a), a value of type c and a callback f(a) -> c, \n"
    " returns the value of type c if the option is None, else\n"
    " applies the callback to the option's payload.\n"
    "\n"
    " ## Examples\n"
    "\n"
    " ```gleam\n"
    " use payload <- on.none_some(\n"
    "   Some(3),\n"
    "   on_none: \"Bob\",\n"
    " )\n"
    " // -> execution proceeds, payload == 3; the scope must return a\n"
    " // String to match the return value of the on_none return value\n"
    " ```\n"
    "\n"
    " ```gleam\n"
    " use payload <- on.none_some(\n"
    "   None,\n"
    "   on_none: \"Bob\",\n"
    " )\n"
    " // -> execution discontinues, scope returns \"Bob\"\n"
    " ```\n"
).
-spec none_some(gleam@option:option(DVJ), DVL, fun((DVJ) -> DVL)) -> DVL.
none_some(Option, C, F2) ->
    case Option of
        none ->
            C;

        {some, A} ->
            F2(A)
    end.

-file("src/on.gleam", 486).
?DOC(
    " Given an Option(a), a callback f() -> c and a callback\n"
    " f(a) -> c evaluates the first callback if the option is\n"
    " None, else evaluates the second callback on the option's\n"
    " payload.\n"
    "\n"
    " ### Example 1\n"
    "\n"
    " ```gleam\n"
    " use payload <- on.lazy_none_some(\n"
    "   Some(3),\n"
    "   on_none: fn() { \"Bob\" },\n"
    " )\n"
    " // -> execution proceeds, payload == 3; the scope must return\n"
    " // a String to match the return value of the on_none return\n"
    " // value\n"
    " ```\n"
    "\n"
    " ### Example 2\n"
    " \n"
    " ```gleam\n"
    " use payload <- on.lazy_none_some(\n"
    "   None,\n"
    "   on_none: fn() { \"Bob\" },\n"
    " )\n"
    " // -> execution discontinues, scope returns \"Bob\"\n"
    " ```\n"
).
-spec lazy_none_some(
    gleam@option:option(DVM),
    fun(() -> DVO),
    fun((DVM) -> DVO)
) -> DVO.
lazy_none_some(Option, F1, F2) ->
    case Option of
        none ->
            F1();

        {some, A} ->
            F2(A)
    end.

-file("src/on.gleam", 523).
?DOC(
    " Given an Option(a), a callback f(a) -> c and a callback\n"
    " f() -> c, evaluates the first callback on the option's\n"
    " payload, else evaluates the second callback if the option\n"
    " is None.\n"
    "\n"
    " ### Example 1\n"
    "\n"
    " ```gleam\n"
    " use <- on.some_none(\n"
    "   Some(3),\n"
    "   on_some: fn(x) { x + 1 },\n"
    " )\n"
    " // -> execution discontinues, scope returns 4\n"
    " ```\n"
    "\n"
    " ### Example 2\n"
    "\n"
    " ```gleam\n"
    " use <- on.some_none(\n"
    "   None,\n"
    "   on_some: fn(x) { x + 1 },\n"
    " )\n"
    " // -> execution proceeds, the scope must return an Int to match\n"
    " // the return value of the on_some return value\n"
    " ```\n"
).
-spec some_none(gleam@option:option(DVP), fun((DVP) -> DVR), fun(() -> DVR)) -> DVR.
some_none(Option, F1, F2) ->
    case Option of
        {some, A} ->
            F1(A);

        none ->
            F2()
    end.

-file("src/on.gleam", 559).
?DOC(
    " Given a List(a) and a callback\n"
    " f(a, List(a)) -> List(c), returns the empty list if the\n"
    " list is empty, else evaluates the callback on (first, rest)\n"
    " where 'first' is the first element and 'tail' is the tail of \n"
    " the list.\n"
    " \n"
    " ### Example 1\n"
    " \n"
    " ```gleam\n"
    " use first, rest <- on.nonempty([1, 4, 7])\n"
    " // -> execution proceeds, first == 1, rest == [1, 7];\n"
    " // scope must return a List(c)\n"
    " ```\n"
    " \n"
    " ### Example 2\n"
    " \n"
    " ```gleam\n"
    " use first, rest <- on.nonempty([])\n"
    " // -> execution discontinues, scope returns []\n"
    " ```\n"
).
-spec nonempty(list(DVS), fun((DVS, list(DVS)) -> list(DVV))) -> list(DVV).
nonempty(List, F2) ->
    case List of
        [] ->
            [];

        [First | Rest] ->
            F2(First, Rest)
    end.

-file("src/on.gleam", 587).
?DOC(
    " Given a List(a) and a callback f() -> List(a)\n"
    " returns the list if the is nonempty, else evaluates\n"
    " the callback.\n"
    "\n"
    " ### Example 1\n"
    " \n"
    " ```gleam\n"
    " use <- on.empty([1, 4, 7])\n"
    " // -> execution discontinues, scope returns [1, 4, 7]\n"
    " ```\n"
    " \n"
    " ### Example 2\n"
    " \n"
    " ```gleam\n"
    " use <- on.empty([])\n"
    " // -> execution proceeds, the scope must return a List(c)\n"
    " ```\n"
).
-spec empty(list(DVY), fun(() -> list(DVY))) -> list(DVY).
empty(List, F2) ->
    case List of
        [_ | _] ->
            List;

        [] ->
            F2()
    end.

-file("src/on.gleam", 628).
?DOC(
    " Given a List(a), a value of type c, and callback\n"
    " f(a, List(a)) -> c, returns either the value of type c\n"
    " if the list is empty or else applies the callback to \n"
    " the head: a and tail: List(a) of the list.\n"
    " \n"
    " ### Example 1\n"
    " \n"
    " ```gleam\n"
    " use first, rest <- on.empty_nonempty(\n"
    "   [1, 4, 7],\n"
    "   on_empty: \"Joe\",\n"
    " )\n"
    " // -> execution proceeds, first == 1, rest == [4, 7];\n"
    " // scope must return a String to match the empty list\n"
    " // return value\n"
    " ```\n"
    " \n"
    " ### Example 2\n"
    " \n"
    " ```gleam\n"
    " use first, rest <- on.empty_nonempty(\n"
    "   [],\n"
    "   on_empty: \"Joe\",\n"
    " )\n"
    " // -> execution discontinues, scope returns \"Joe\"\n"
    " ```\n"
).
-spec empty_nonempty(list(DWC), DWE, fun((DWC, list(DWC)) -> DWE)) -> DWE.
empty_nonempty(List, C, F2) ->
    case List of
        [] ->
            C;

        [First | Rest] ->
            F2(First, Rest)
    end.

-file("src/on.gleam", 666).
?DOC(
    " Given a List(a), a callback fn() -> c and a callback\n"
    " f(a, List(a)) -> c, evaluates the first callback if the\n"
    " list is empty else applies the second callback to the\n"
    " head: a and tail: List(a) of the list.\n"
    " \n"
    " ### Example 1\n"
    " \n"
    " ```gleam\n"
    " use first, rest <- on.lazy_empty_nonempty(\n"
    "   [1, 4, 7],\n"
    "   on_empty: fn() { \"Joe\" },\n"
    " )\n"
    " // -> execution proceeds, first == 1, rest == [4, 7];\n"
    " // scope must return a String to match the empty list\n"
    " // callback return value\n"
    " ```\n"
    " \n"
    " ### Example 2\n"
    " \n"
    " ```gleam\n"
    " use first, rest <- on.lazy_empty_nonempty(\n"
    "   [],\n"
    "   on_empty: fn() { \"Joe\" },\n"
    " )\n"
    " // -> execution discontinues, scope returns \"Joe\"\n"
    " ```\n"
).
-spec lazy_empty_nonempty(
    list(DWG),
    fun(() -> DWI),
    fun((DWG, list(DWG)) -> DWI)
) -> DWI.
lazy_empty_nonempty(List, F1, F2) ->
    case List of
        [] ->
            F1();

        [First | Rest] ->
            F2(First, Rest)
    end.

-file("src/on.gleam", 705).
?DOC(
    " Given a List(a), a callback  f(a, List(a)) -> c, and\n"
    " a callback f() -> c, returns either the first callback\n"
    " evaluated on the first element and tail of the list if\n"
    " the list is nonempty, and otherwise evaluates the \n"
    " second callback, if the list is empty. \n"
    " \n"
    " ### Example 1\n"
    " \n"
    " ```gleam\n"
    " use <- on.nonempty_empty(\n"
    "   [1, 4, 7],\n"
    "   fn(first, _rest) { first + 1 },\n"
    " )\n"
    " // -> execution discontinues, scope returns 2\n"
    " ```\n"
    " \n"
    " ### Example 2\n"
    " \n"
    " ```gleam\n"
    " use <- on.nonempty_empty(\n"
    "   [],\n"
    "   fn(first, _rest) { first + 1 },\n"
    " )\n"
    " // -> execution proceeds, the scope must return an\n"
    " // integer to match the return value of the first\n"
    " // callback\n"
    " ```\n"
).
-spec nonempty_empty(list(DWK), fun((DWK, list(DWK)) -> DWN), fun(() -> DWN)) -> DWN.
nonempty_empty(List, F1, F2) ->
    case List of
        [First | Rest] ->
            F1(First, Rest);

        [] ->
            F2()
    end.

-file("src/on.gleam", 750).
?DOC(
    " Given a List(a), a value of type c, and callbacks\n"
    " f(a) -> c, f(a, a, List(a)) -> c, returns:\n"
    "\n"
    " - the value of type c if the list is empty\n"
    " - the first callback evaluated with argument a1 if the list as the form [a1]\n"
    " - the second callback evaluated with arguments a1, a2, rest if the list has the form [a1, a2, ..rest]\n"
    " \n"
    " ### Example 1\n"
    " \n"
    " ```gleam\n"
    " use first, second, ..rest <- on.empty_singleton_gt1(\n"
    "   [1, 4, 7],\n"
    "   on_empty: 0,\n"
    "   on_singleton: fn(first) { first },\n"
    " )\n"
    " // -> execution proceeds, first == 1, second == 4, rest == [7];\n"
    " // scope must return an Int to match the on_empty, on_singleton callbacks\n"
    " ```\n"
    " \n"
    " ### Example 2\n"
    " \n"
    " ```gleam\n"
    " use first, second, ..rest <- on.empty_singleton_gt1(\n"
    "   [4],\n"
    "   on_empty: 0,\n"
    "   on_singleton: fn(first) { first },\n"
    " )\n"
    " // -> execution discontinues, scope resturns 4\n"
    " ```\n"
).
-spec empty_singleton_gt1(
    list(DWO),
    DWQ,
    fun((DWO) -> DWQ),
    fun((DWO, DWO, list(DWO)) -> DWQ)
) -> DWQ.
empty_singleton_gt1(List, C, F2, F3) ->
    case List of
        [] ->
            C;

        [First] ->
            F2(First);

        [First@1, Second | Rest] ->
            F3(First@1, Second, Rest)
    end.

-file("src/on.gleam", 793).
?DOC(
    " Given a List(a), and callbacks f() -> c, f(a) -> c,\n"
    " f(a, a, List(a)) -> c, returns:\n"
    "\n"
    " - the evaluation of the first callback if the list is empty\n"
    " - the second callback evaluated with argument a1 if the list as the form [a1]\n"
    " - the third callback evaluated with arguments a1, a2, rest if the list has the form [a1, a2, ..rest]\n"
    " \n"
    " ### Example 1\n"
    " \n"
    " ```gleam\n"
    " use first, second, ..rest <- on.lazy_empty_singleton_gt1(\n"
    "   [1, 4, 7],\n"
    "   on_empty: 0,\n"
    "   on_singleton: fn(first) { first },\n"
    " )\n"
    " // -> execution proceeds, first == 1, second == 4, rest == [7];\n"
    " // scope must return an Int to match the on_empty, on_singleton callbacks\n"
    " ```\n"
    " \n"
    " ### Example 2\n"
    " \n"
    " ```gleam\n"
    " use first, second, ..rest <- on.lazy_empty_singleton_gt1(\n"
    "   [4],\n"
    "   on_empty: 0,\n"
    "   on_singleton: fn(first) { first },\n"
    " )\n"
    " // -> execution discontinues, scope resturns 4\n"
    " ```\n"
).
-spec lazy_empty_singleton_gt1(
    list(DWS),
    fun(() -> DWU),
    fun((DWS) -> DWU),
    fun((DWS, DWS, list(DWS)) -> DWU)
) -> DWU.
lazy_empty_singleton_gt1(List, F1, F2, F3) ->
    case List of
        [] ->
            F1();

        [First] ->
            F2(First);

        [First@1, Second | Rest] ->
            F3(First@1, Second, Rest)
    end.

-file("src/on.gleam", 837).
?DOC(
    " Given a List(a), a value of type c, and callbacks\n"
    " f(a, a, List(a)) -> c, f(a) -> c, returns:\n"
    "\n"
    " - the value of type c if the list is empty\n"
    " - the first callback evaluated with arguments a1, a2, rest if the list has the form [a1, a2, ..rest]\n"
    " - the second callback evaluated with argument a1 if the list as the form [a1]\n"
    " \n"
    " ### Example 1\n"
    " \n"
    " ```gleam\n"
    " use first <- on.empty_gt1_singleton(\n"
    "   [1, 4, 7],\n"
    "   on_empty: Error(\"empty list\"),\n"
    "   on_gt1: Error(\"> 1 element in list\"),\n"
    " )\n"
    " // -> execution discontinues, scope returns Error(\"> 1 element in list\")\n"
    " ```\n"
    " \n"
    " ### Example 2\n"
    " \n"
    " ```gleam\n"
    " use first <- on.empty_gt1_singleton(\n"
    "   [4],\n"
    "   on_empty: Error(\"empty list\"),\n"
    "   on_gt1: Error(\"> 1 element in list\"),\n"
    " )\n"
    " // -> execution proceeds, first == 4;\n"
    " // scope must return a Result(c, String) to match the on_empty \n"
    " // and on_gt1 callbacks\n"
    " ```\n"
).
-spec empty_gt1_singleton(
    list(DWW),
    DWY,
    fun((DWW, DWW, list(DWW)) -> DWY),
    fun((DWW) -> DWY)
) -> DWY.
empty_gt1_singleton(List, C, F2, F3) ->
    case List of
        [] ->
            C;

        [First, Second | Rest] ->
            F2(First, Second, Rest);

        [First@1] ->
            F3(First@1)
    end.

-file("src/on.gleam", 881).
?DOC(
    " Given a List(a) and callbacks f() -> c,\n"
    " f(a, a, List(a)) -> c, f(a) -> c, returns:\n"
    "\n"
    " - the evaluation of the first callback if the list is empty\n"
    " - the second callback evaluated with arguments a1, a2, rest if the list has the form [a1, a2, ..rest]\n"
    " - the third callback evaluated with argument a1 if the list as the form [a1]\n"
    " \n"
    " ### Example 1\n"
    " \n"
    " ```gleam\n"
    " use first <- on.lazy_empty_gt1_singleton(\n"
    "   [1, 4, 7],\n"
    "   on_empty: Error(\"empty list\"),\n"
    "   on_gt1: fn(_, _, _) {Error(\"> 1 element in list\")},\n"
    " )\n"
    " // -> execution discontinues, scope returns Error(\"> 1 element in list\")\n"
    " ```\n"
    " \n"
    " ### Example 2\n"
    " \n"
    " ```gleam\n"
    " use first <- on.lazy_empty_gt1_singleton(\n"
    "   [4],\n"
    "   on_empty: Error(\"empty list\"),\n"
    "   on_gt1: Error(\"> 1 element in list\"),\n"
    " )\n"
    " // -> execution proceeds, first == 4;\n"
    " // scope must return a Result(c, String) to match the on_empty \n"
    " // and on_gt1 callbacks\n"
    " ```\n"
).
-spec lazy_empty_gt1_singleton(
    list(DXA),
    fun(() -> DXC),
    fun((DXA, DXA, list(DXA)) -> DXC),
    fun((DXA) -> DXC)
) -> DXC.
lazy_empty_gt1_singleton(List, F1, F2, F3) ->
    case List of
        [] ->
            F1();

        [First, Second | Rest] ->
            F2(First, Second, Rest);

        [First@1] ->
            F3(First@1)
    end.

-file("src/on.gleam", 925).
?DOC(
    " Given a List(a) and callbacks f(a) -> c,\n"
    " f(a, a, List(a)) -> c, f() -> c, returns:\n"
    "\n"
    " - the first callback evaluated with argument a1 if the list as the form [a1]\n"
    " - the second callback evaluated with arguments a1, a2, rest if the list has the form [a1, a2, ..rest]\n"
    " - the evaluation of the third callback if the list is empty\n"
    " \n"
    " ### Example 1\n"
    " \n"
    " ```gleam\n"
    " use <- on.singleton_gt1_empty(\n"
    "   [1, 4, 7],\n"
    "   on_singleton: fn(x) { x + 1 },\n"
    "   on_gt1: fn(first, second, ..rest) { first + second},\n"
    " )\n"
    " // -> execution discontinues, scope returns 5 (= 1 + 4)\n"
    " ```\n"
    " \n"
    " ### Example 2\n"
    " \n"
    " ```gleam\n"
    " use first, second, ..rest <- on.singleton_gt1_empty(\n"
    "   [],\n"
    "   on_singleton: fn(x) { x + 1 },\n"
    "   on_gt1: fn(first, second, ..rest) { first + second},\n"
    " )\n"
    " // -> execution proceeds, scope must return an Int to \n"
    " // match the on_singleton, on_gt1 callbacks\n"
    " \n"
    " ```\n"
).
-spec singleton_gt1_empty(
    list(DXE),
    fun((DXE) -> DXG),
    fun((DXE, DXE, list(DXE)) -> DXG),
    fun(() -> DXG)
) -> DXG.
singleton_gt1_empty(List, F1, F2, F3) ->
    case List of
        [First] ->
            F1(First);

        [First@1, Second | Rest] ->
            F2(First@1, Second, Rest);

        [] ->
            F3()
    end.

-file("src/on.gleam", 938).
-spec main() -> nil.
main() ->
    gleam_stdlib:println(<<"Hello from on!"/utf8>>).