fixed

commit 96a2b9d525c9ec2eda06e46b9128abaae5497931
parent 33d61325056e4e3622768b153faaaa57c90cefbc
Author: Jared Tobin <jared@jtobin.io>
Date:   Sat, 20 Dec 2025 15:11:07 -0330

lib: used unboxed sum for sqrt#

Diffstat:
M
lib/Numeric/Montgomery/Secp256k1/Curve.hs
 | 
16
+++++++---------

1 file changed, 7 insertions(+), 9 deletions(-)
diff --git a/lib/Numeric/Montgomery/Secp256k1/Curve.hs b/lib/Numeric/Montgomery/Secp256k1/Curve.hs
@@ -997,16 +997,14 @@ inv (Montgomery w) = Montgomery (inv# w)
 --   >>> (*) <$> sqrt 15 <*> sqrt 15
 --   Just 15
 sqrt :: Montgomery -> Maybe Montgomery
-sqrt (Montgomery n) =
-  let !rv = sqrt# n
-  in  if   C.decide (WW.eq# (sqr# rv) n)
-      then Just $! Montgomery rv
-      else Nothing
+sqrt (Montgomery n) = case sqrt# n of
+  (# a | #) -> Just $! Montgomery a
+  _         -> Nothing
 
 -- generated by etc/generate_sqrt.sh
 sqrt#
   :: (# Limb, Limb, Limb, Limb #)
-  -> (# Limb, Limb, Limb, Limb #)
+  -> (# (# Limb, Limb, Limb, Limb #) | () #)
 sqrt# a =
   let !t0 = (# Limb 0x1000003D1##, Limb 0##, Limb 0##, Limb 0## #)
       !t1 = sqr# t0
@@ -1513,11 +1511,11 @@ sqrt# a =
       !t502 = sqr# t501
       !t503 = sqr# t502
       !r = t503
-  in  r
+  in  if   C.decide (WW.eq# (sqr# r) a)
+      then (# r | #)
+      else (# | () #)
 {-# INLINE sqrt# #-}
 
--- XX want unboxed variants
-
 -- | Exponentiation in the Montgomery domain.
 --
 --   >>> exp 2 3