dhall-1.24.0: dhall-lang/Prelude/Optional/fold

{-
`fold` is the primitive function for consuming `Optional` values

Examples:

```
./fold Natural (Some 2) Natural (λ(x : Natural) → x) 0 = 2

./fold Natural (None Natural) Natural (λ(x : Natural) → x) 0 = 0
```
-}
let fold
    :   ∀(a : Type)
      → Optional a
      → ∀(optional : Type)
      → ∀(some : a → optional)
      → ∀(none : optional)
      → optional
    = Optional/fold

in  fold