11 Oct
2007
11 Oct
'07
12:45 a.m.
On 10/10/07, Dan Weston
Actually, it is a constant: piDecimalExpansion :: String.
Where is this constant defined?
A translation from piDecimalExpansion :: String to pi :: Floating a => a is already well defined via read :: Read a => String -> a
Any definition of pi in the Floating class that differs from (read piDecimalExpansion) is erroneous. I propose the above as the default definition of pi.
piDecimalExpansion, if defined, would be an infinite length string. The expression read $ "0." ++ repeat '1' :: Double is Bottom. So even if you had piDecimalExpansion, it isn't clear how to use that to define pi.