diff options
Diffstat (limited to 'src/Core/Thinning.idr')
| -rw-r--r-- | src/Core/Thinning.idr | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/src/Core/Thinning.idr b/src/Core/Thinning.idr index dc4efcb..a2500e9 100644 --- a/src/Core/Thinning.idr +++ b/src/Core/Thinning.idr @@ -68,3 +68,18 @@ export wkn : Fin m -> m `Thins` n -> Fin n wkn i IsId = i wkn i (IsThinner thin) = wkn' i thin + +-- Composition ----------------------------------------------------------------- + +comp : Thinner m n -> Thinner k m -> Thinner k n +comp IsBase thin2 = IsDrop thin2 +comp (IsDrop thin1) thin2 = IsDrop (comp thin1 thin2) +comp (IsKeep thin1) IsBase = IsDrop thin1 +comp (IsKeep thin1) (IsDrop thin2) = IsDrop (comp thin1 thin2) +comp (IsKeep thin1) (IsKeep thin2) = IsKeep (comp thin1 thin2) + +export +(.) : m `Thins` n -> k `Thins` m -> k `Thins` n +IsId . thin2 = thin2 +IsThinner thin1 . IsId = IsThinner thin1 +IsThinner thin1 . IsThinner thin2 = IsThinner (comp thin1 thin2) |