# `Feel.Value.Date`
[🔗](https://github.com/FeeJai/BDM/blob/feel-v0.1.0/apps/feel/lib/feel/value/date.ex#L1)

The FEEL type `date` (DMN 1.6, section 10.3.2.3.5).

A date is a year, month, and day in the proleptic Gregorian calendar, with a
year from -999,999,999 to 999,999,999. It has no time of day and no time zone.
It is represented as an Elixir `Date` in the ISO calendar, which covers the
whole FEEL year range.

A `date` does not conform to `date and time`, although it converts to one at
midnight UTC where an implicit conversion applies.

# `t`

```elixir
@type t() :: Date.t()
```

# `new`

```elixir
@spec new(integer(), integer(), integer()) :: {:ok, t()} | :error
```

Builds a date.

Returns `:error` when the combination of year, month, and day is not a date, or
the year is outside the FEEL range.

    iex> Feel.Value.Date.new(2026, 10, 12)
    {:ok, ~D[2026-10-12]}
    iex> Feel.Value.Date.new(2026, 2, 30)
    :error
    iex> Feel.Value.Date.new(1_000_000_000, 1, 1)
    :error

# `parse`

```elixir
@spec parse(String.t()) :: {:ok, t()} | :error
```

Parses a date string, as `date("...")` and `@"..."` read it: `YYYY-MM-DD`, the
lexical space of the XML Schema `date` (DMN 1.6, section 10.3.4.1).

The year has at least four digits and may be negative. White space around the
string is ignored. The zone that XML Schema allows after the day (`Z`, `+01:00`)
is accepted and dropped, since a date has none (notes 06, AE-4, D-54). Returns
`:error` for anything else, including a day that the month does not have.

    iex> Feel.Value.Date.parse("2026-10-12")
    {:ok, ~D[2026-10-12]}
    iex> Feel.Value.Date.parse(" -0044-03-15 ")
    {:ok, Date.new!(-44, 3, 15)}
    iex> Feel.Value.Date.parse("2012-12-25+01:00")
    {:ok, ~D[2012-12-25]}
    iex> Feel.Value.Date.parse("2011-02-30")
    :error
    iex> Feel.Value.Date.parse("2012-12-25T10:00:00")
    :error

# `type`

```elixir
@spec type() :: Feel.Type.t()
```

Returns the type descriptor of `date`.

# `value?`

```elixir
@spec value?(term()) :: boolean()
```

Returns `true` for an ISO-calendar `Date` within the FEEL year range.

    iex> Feel.Value.Date.value?(~D[2026-10-12])
    true
    iex> Feel.Value.Date.value?(~N[2026-10-12 00:00:00])
    false

---

*Consult [api-reference.md](api-reference.md) for complete listing*