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:t doesn't work correctly in Playground

Eric Zoerner

July 20, 2017 21:06

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 :t seems to just echo the expression given it instead of (also) giving the type.

For example,

:t 1 + 1

results in:

1 + 1

but it should result in:

1 + 1 :: Num a => a

 

Version of Haskell for Mac is 1.5.0

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5 comments

• 
  Manuel Chakravarty July 21, 2017 00:32 Official comment

  Thank you for this bug report. This is a regression in 1.5.0.

  In the meantime, you can select the expression and press CMD-I to get its type.

  I am sorry for the inconvenience. This will be fixed in the upcoming bug fix release.

• 0
  
  Manuel Chakravarty July 25, 2017 05:28

  I have been looking into this more closely and have trouble reproducing it now. Here is what I get

  

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  Eric Zoerner July 25, 2017 15:16

  Interesting.

  I am able reproduce that as well until and unless you type a line feed after the expression.

  It seems that if there is a line feed anywhere on the line after the :t expression, then it will only echo the expression and not show the type.

  Edited by Eric Zoerner July 25, 2017 15:18
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  Manuel Chakravarty July 26, 2017 00:51

  Thank you for the clarification. I can in fact reproduce that. (That's why my unit test didn't catch it.) Thanks!

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  Manuel Chakravarty July 26, 2017 00:54

  BTW, this is only a formatting problem. The correct type is actually in the output, you just can't see it as it is outside the clipped area due to the newline character. You can see that if you right click the `1 + 1` in the result area (to get a popup menu) and select "Show Type".

  I hope that can serve as a work around until I put out a bug fix release.

  Edited by Manuel Chakravarty July 26, 2017 00:55