Define FieldElement substraction and multiplication

1 files changed, 29 insertions, 0 deletions

diff --git a/ecc.hs b/ecc.hs
index 6271864..200b613 100644
--- a/ecc.hs
+++ b/ecc.hs
@@ -13,3 +13,32 @@ add :: FieldElement -> FieldElement -> FieldElement
 add (FieldElement a b) (FieldElement c d)
   | b /= d = error "Distinct Fields"
   | otherwise = FieldElement (mod (a + c) b) b
+
+sub :: FieldElement -> FieldElement -> FieldElement
+sub (FieldElement a b) (FieldElement c d)
+  | b /= d = error "Distinct Fields"
+  | otherwise = FieldElement (mod (a - c) b) b
+
+mul :: FieldElement -> FieldElement -> FieldElement
+mul (FieldElement a b) (FieldElement c d)
+  | b /= d = error "Distinct Fields"
+  | otherwise = FieldElement (mod (a * c) b) b
+
+assert :: Bool -> Bool
+assert False = error "WRONG"
+assert x = x
+
+aa =
+  let a = FieldElement 2 31
+      b = FieldElement 15 31
+   in assert
+        (and
+           [ add a b == FieldElement 17 31
+           , a /= b
+           , sub a b == FieldElement 18 31
+           ])
+
+bb =
+  let a = FieldElement 19 31
+      b = FieldElement 24 31
+   in mul a b