fixed

commit 332c5afeb524ce51da6decde6b1d7609f3e06781
parent c701ecb51224ffc087ce43c11f5d97cc3f11b22e
Author: Jared Tobin <jared@jtobin.io>
Date:   Fri, 21 Nov 2025 17:27:11 +0400

lib: add 'decide' for Choice

Diffstat:
M
lib/Data/Choice.hs
 | 
7
+++++++
M
lib/Data/Word/Wider.hs
 | 
6
------

2 files changed, 7 insertions(+), 6 deletions(-)
diff --git a/lib/Data/Choice.hs b/lib/Data/Choice.hs
@@ -9,6 +9,7 @@ module Data.Choice (
     Choice
   , true#
   , false#
+  , decide
 
   -- * MaybeWord#
   , MaybeWord#(..)
@@ -127,6 +128,10 @@ true# _ = case maxBound :: Word of
   W# w -> Choice w
 {-# INLINE true# #-}
 
+decide :: Choice -> Bool
+decide (Choice c) = isTrue# (neWord# c 0##)
+{-# INLINE decide #-}
+
 -- constant time 'Maybe Word#'
 newtype MaybeWord# = MaybeWord# (# Word#, Choice #)
 
@@ -274,6 +279,8 @@ ct_select_wide# a b (Choice w) =
   in  xor_w# a (and_w# mask (xor_w# a b))
 {-# INLINE ct_select_wide# #-}
 
+-- constant-time equality -----------------------------------------------------
+
 ct_eq_word# :: Word# -> Word# -> Choice
 ct_eq_word# a b =
   let !s = case B.finiteBitSize (0 :: Word) of I# m -> m -# 1#
diff --git a/lib/Data/Word/Wider.hs b/lib/Data/Word/Wider.hs
@@ -36,12 +36,6 @@ instance Show Wider where
        "(" <> show (W# a) <> ", " <> show (W# b) <> ", "
     <> show (W# c) <> ", " <> show (W# d) <> ")"
 
-instance Eq Wider where
-  Wider (# a0, b0, c0, d0 #) == Wider (# a1, b1, c1, d1 #) =
-    isTrue# (andI#
-      ((andI# (eqWord# a0 a1) (eqWord# b0 b1)))
-      ((andI# (eqWord# c0 c1) (eqWord# d0 d1))))
-
 instance NFData Wider where
   rnf (Wider a) = case a of (# _, _, _, _ #) -> ()