[GHC] #7045: The `Read` instance of `Rational` does not support exponential notation

[GHC]

#7045: The `Read` instance of `Rational` does not support exponential notation
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  Reporter:  maeder            |          Owner:                  
      Type:  bug               |         Status:  new             
  Priority:  normal            |      Milestone:  7.6.1           
 Component:  libraries/base    |        Version:  7.4.2           
Resolution:                    |       Keywords:                  
        Os:  Unknown/Multiple  |   Architecture:  Unknown/Multiple
   Failure:  None/Unknown      |     Difficulty:  Unknown         
  Testcase:                    |      Blockedby:                  
  Blocking:                    |        Related:  #7044, #5692    
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Comment(by maeder):

 Maybe worse is, that the decimal point is not supported?

 If (real) floating point literals would be converted only for numbers in
 the class `RealFloat`, then my original issue (namely, same behavior as
 literal or as read argument) would be trivially solved.

 But that is a design decision (to be taken considering the related
 tickets).

 (My design would distinguish ints, fractionals and floats.)

 If you miss "1e10" as Rational then why not as Integer? (I would leave
 using "{{{^}}}" to the user.)

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7045#comment:6>
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