[Haskell-cafe] newbie timing question

[Donald Bruce Stewart]

seanmcl:
> 
> Hello,
> 
> I'm trying to write a simple function to time an application.
> 
> -- this doesn't work
> 
> time f x =
>   do n1 <- CPUTime.getCPUTime
>      let res = f x in
>        do n2 <- CPUTime.getCPUTime
>           return (res,n2 - n1)
> 
> On a function that takes 8 seconds to complete, returns
> (True,46000000)
> 
> According to the documentation, this time is in picoseconds, making
> this 46 microseconds.

That thunk you're allocating with 'let' isn't going to help much ;)

  http://haskell.org/haskellwiki/Timing_computations

Cheers,
  Don