Idris2-boot/tests/idris2/interface008/Deps.idr

data Fin : Nat -> Type where
     FZ : Fin (S k)
     FS : Fin k -> Fin (S k)

interface Finite t where
  0 card   : Nat
  to     : t -> Fin card

implementation Finite (Fin k) where
  card = k
  to = id

interface BadFinite t where
  badcard   : Nat
  badto     : t -> Fin card

implementation BadFinite (Fin k) where
  badcard = k
  badto = id
Allow marking interface methods multiplicities Now by marking a method as multiplicity 0, we can explicitly say that it's compile time only, so we can use it to compute types based on other erased things - see tests/idris2/interface008 for a small example. This fixes #8 - at least in that it allows the interface to be expressed properly now, although the multiplicity annotations mean that unfortunately it can't be compatible with Idris 1. 2019-07-22 18:21:33 +03:00			`data Fin : Nat -> Type where`
			`FZ : Fin (S k)`
			`FS : Fin k -> Fin (S k)`

			`interface Finite t where`
			`0 card : Nat`
			`to : t -> Fin card`

			`implementation Finite (Fin k) where`
			`card = k`
			`to = id`

			`interface BadFinite t where`
			`badcard : Nat`
			`badto : t -> Fin card`

			`implementation BadFinite (Fin k) where`
			`badcard = k`
			`badto = id`