Haskell could not read this double: ".3". This is mistake?

Question

GHC Haskell seems to require a number before the decimal point to read Double. Here is the code:

main :: IO ()
main = do
  let d1 = read "0.3" :: Double
      d2 = read ".3"  :: Double      
  print d1
  print d2

Running this process:

0.3
*** Exception: Prelude.read: no parse

Is this a GHC bug or just a major limitation?

(I tried reading ".3" using C, Javascript and MS Excel, and all of this could successfully parse ".3" and understand it as a number. I think I see the consequences of this problem in other areas of my program, including reading arguments command line with parseargs package and reading paired in html forms with Yesod MForms.)

Is there a fix or workaround for this issue?

Answer 1

iand675, , :

Haskell, Read, Haskell. , Haskell, , - .

, Haskell.

Answer 2

Haskell:

2.5

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