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Surprising behaviour of Scientific arithmetic inside a template #271

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cblp opened this issue Oct 28, 2022 · 1 comment

cblp commented Oct 28, 2022

> let a = 1 :: Scientific in [st|#{show $ 0.1 * a}|]
<interactive>:74:32-50: Splicing expression
    quoteExp st "#{show $ 0.1 * a}"
  ======>
    (toStrict . toLazyText) (toText (show (((*) 0.1) a)))
"0.1000000000000000055511151231257827021181583404541015625"

> let a = 1 :: Scientific in (toStrict . toLazyText) (toText (show (((*) 0.1) a)))
"0.1"

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cblp commented Oct 28, 2022

> realToFrac (0.1 :: Double) :: Scientific
0.1000000000000000055511151231257827021181583404541015625

looks like Shakespeare's parser treats 0.1 as Double, not Rational like GHC does.

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