From: simonpj <unknown>
Date: Fri, 14 Jun 2002 08:17:08 +0000 (+0000)
Subject: [project @ 2002-06-14 08:17:08 by simonpj]
X-Git-Tag: nhc98-1-18-release~976
X-Git-Url: http://git.megacz.com/?a=commitdiff_plain;h=1ded2c9515562bbe3a231f7cb66a931cf7513718;p=ghc-base.git

[project @ 2002-06-14 08:17:08 by simonpj]
Add comment
---

diff --git a/Text/Read/Lex.hs b/Text/Read/Lex.hs
index 290072b..f2c0469 100644
--- a/Text/Read/Lex.hs
+++ b/Text/Read/Lex.hs
@@ -288,6 +288,17 @@ infinity, notANumber :: Rational
 infinity   = 1 :% 0
 notANumber = 0 :% 0
 
+-- Use :%, not % for Inf/NaN, the latter would 
+-- immediately lead to a runtime error. 
+--
+-- Note that
+--     isInfinite (read "Infinity" :: Float)
+--  or
+--     isInfinite (fromRational (1 :% 0))
+-- still don't work, because fromRational is not OK for those cases.
+-- 
+-- The whole Infinity/NaN story is a bit murky to me
+
 type Base   = Int
 type Digits = [Int]