1 files changed, 55 insertions, 0 deletions
diff --git a/src/Inky/Data/Fun.idr b/src/Inky/Data/Fun.idr
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+++ b/src/Inky/Data/Fun.idr
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+module Inky.Data.Fun
+
+import public Inky.Data.SnocList.Quantifiers
+import Inky.Data.SnocList
+
+public export
+Fun : SnocList Type -> Type -> Type
+Fun [<] b = b
+Fun (as :< a) b = Fun as (a -> b)
+
+public export
+chain : (len : LengthOf as) -> (b -> c) -> Fun as b -> Fun as c
+chain Z f x = f x
+chain (S len) f g = chain len (f .) g
+
+public export
+DFun : (as : SnocList Type) -> Fun as Type -> Type
+DFun [<] p = p
+DFun (as :< a) p = DFun as (chain (lengthOf as) (\f => (x : a) -> f x) p)
+
+public export
+DIFun : (as : SnocList Type) -> Fun as Type -> Type
+DIFun [<] p = p
+DIFun (as :< a) p = DIFun as (chain (lengthOf as) (\f => {x : a} -> f x) p)
+
+public export
+curry : (len : LengthOf as) -> (HSnocList as -> b) -> Fun as b
+curry Z f = f [<]
+curry (S len) f = curry len (f .: (:<))
+
+public export
+uncurry : Fun as b -> HSnocList as -> b
+uncurry f [<] = f
+uncurry f (sx :< x) = uncurry f sx x
+
+export
+uncurryChain :
+  (0 g : b -> c) -> (0 f : Fun as b) -> (xs : HSnocList as) ->
+  uncurry (chain (lengthOf as) g f) xs = g (uncurry f xs)
+uncurryChain g f [<] = Refl
+uncurryChain g f (sx :< x) = cong (\f => f x) (uncurryChain (g .) f sx)
+
+export
+dcurry : (len : LengthOf as) -> ((xs : HSnocList as) -> uncurry p xs) -> DFun as p
+dcurry Z f = f [<]
+dcurry (S len) f =
+  dcurry len (\sx =>
+    replace {p = id} (sym $ uncurryChain (\f => (x : _) -> f x) p sx)
+      (\x => f (sx :< x)))
+
+export
+duncurry : DFun as p -> (sx : HSnocList as) -> uncurry p sx
+duncurry f [<] = f
+duncurry f (sx :< x) =
+  replace {p = id} (uncurryChain (\f => (x : _) -> f x) p sx) (duncurry f sx) x