Agreed: this is an upstream issue. Thanks for forwarding.
More info/thoughts.
Plain old
floor $ sqrt (-1)
manifests the issue.
Similar phenomena occur with ceiling instead of floor, and with Inf
instead of Nan.
Prelude> ceiling $ 1/0
179769313486231590772930519078902473361797697894230657273430081157732675805500963132708477322407536021120113879871393357658789768814416622492847430639474124377767893424865485276302219601246094119453082952085005768838150682342462881473913110540827237163350510684586298239947245938479716304835356329624224137216
Prelude> floor $ sqrt (-10^6) :: Int
0
Prelude> floor $ sqrt (-10^6) :: Integer
-269653970229347386159395778618353710042696546841345985910145121736599013708251444699062715983611304031680170819807090036488184653221624933739271145959211186566651840137298227914453329401869141179179624428127508653257226023513694322210869665811240855745025766026879447359920868907719574457253034494436336205824
It seems to me that the function that converts the RealFloat NaN or
Inf into a RealFrac should yield (error "NaN") or (error "Inf"). As
things stand, this is begging for silently incorrect numeric results.
--Barak.
--
Barak A. Pearlmutter
Hamilton Institute & Dept Comp Sci, NUI Maynooth, Co. Kildare, Ireland
http://www.bcl.hamilton.ie/~barak/
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