[Hugs] #69: Pattern match error can be arbitrarily long

[Hugs]

#69: Pattern match error can be arbitrarily long
---------------------+------------------------------------------------------
  Reporter:  neil    |       Owner:  nobody
      Type:  defect  |      Status:  new   
  Priority:  major   |   Milestone:        
 Component:  hugs    |     Version:  200609
Resolution:          |    Keywords:        
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Old description:

> Given the program:
>
>  test n = length val `seq` f val
>      where val = replicate n (toEnum 12)
>
>  f "" = ""
>
>  > test 3
>  Program error: pattern match failure: f [toEnum 12,toEnum 12,toEnum 12]
>
> Unfortunately, as you bump up n (try 10,000) Hugs spits and more and more
> information - when the most important bit of this message is "f" - which
> you end up loosing.
>
> I suggest truncating pattern match errors at (say) 500 characters, or
> perhaps 500 characters per argument.

New description:

 Given the program:

 {{{
 test n = length val `seq` f val
     where val = replicate n (toEnum 12)

 f "" = ""

 > test 3
 Program error: pattern match failure: f [toEnum 12,toEnum 12,toEnum 12]
 }}}

 Unfortunately, as you bump up n (try 10,000) Hugs spits and more and more
 information - when the most important bit of this message is "f" - which
 you end up loosing.

 I suggest truncating pattern match errors at (say) 500 characters, or
 perhaps 500 characters per argument.

-- 
Ticket URL: <http://hackage.haskell.org/trac/hugs/ticket/69>
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