Is traceIO unnecessarily specialised to the IO monad?

Chris Seaton chris at
Mon Jan 21 17:58:21 CET 2013

The user can generate the string however they want. The proposed traceM
does not duplicate any printf functionality, and neither requires nor
prevents the use of printf.

It is more about allowing the user to add trace actions in an arbitrary
monad, rather than just the IO monad. If people want to trace in IO, and we
think it is worth a function to do that, might they not want to trace in
any monad, and it be worth adding a function for that?


On 21 January 2013 16:53, Henning Thielemann
<lemming at>wrote:

> On Mon, 21 Jan 2013, Chris Seaton wrote:
>  Would traceM be a wanted addition to Debug.Trace?
> You can use printf for generating Strings and show them using plain
> 'trace'.
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