# `DpExchange.Core.Types.Funding`
[🔗](https://github.com/DistortionPoint/dp-exchange-core/blob/v0.3.120/lib/dp_exchange/core/types/funding.ex#L1)

A perpetual's funding: what was paid, what is projected, and when the next one lands.

## Settled and estimated are different facts

`:amount` is funding that has **happened** — a payment between longs and shorts at a
funding time that has passed. `:estimated_amount` is the venue's projection for the *next*
one, and it moves continuously until the moment it settles.

They are separate fields for the same reason realised and unrealised P&L are on
`Types.Position`: one is a fact and the other is an opinion, and a caller that books an
estimate has booked a number that had not happened. A venue's own response carries both —
`fundingAmount: -1.50991` beside `estimatedFundingAmount: -2.10595`, differing by 40% —
which is precisely how wrong a caller reading "the funding" would be.

## Sign is the venue's, and it means direction

Funding is a payment between sides. A negative amount means one side paid the other, and
which is which is a venue convention this layer does not reinterpret. **The sign is
carried through unchanged**; a package that normalised it would be asserting a convention
the venue did not state.

## `:next_funding_at` is a scheduling fact

A caller holding a perpetual across a funding time pays or receives at that instant.
Knowing when it is, is the difference between choosing to hold the position and
discovering the payment afterwards.

# `t`

```elixir
@type t() :: %DpExchange.Core.Types.Funding{
  amount: Decimal.t() | nil,
  estimated_amount: Decimal.t() | nil,
  funded_at: DateTime.t() | nil,
  next_funding_at: DateTime.t() | nil,
  provider: atom(),
  symbol: String.t()
}
```

# `new`

```elixir
@spec new(keyword() | map()) :: t()
```

Builds a `t:t/0`, failing closed if a required field is absent or `nil`.

`@enforce_keys` guards presence, not `nil` — see `DpExchange.Core.Types.Validate`.

Also raises on an `:amount` or `:estimated_amount` that is not a number. Neither is held to a
sign: funding is signed, and the sign is the venue's (see the moduledoc).

---

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