This is a brilliant idea, but the implementation is a bit poor in my opinion.
In other tutorials (such as Try Ruby, for example), the input is actually parsed and executed. I've found people like to play around a bit and try things the tutorial doesn't specify, such as grepping a different part of the limerick or catting a different file.
I know it might be hard to implement but it's much more pleasing to have a more complete simulation - I got confused when I tried to grep 'yo-ho-ho' and just got the full limerick (though I haven't used grep much so I might be at fault here)
In other tutorials (such as Try Ruby, for example), the input is actually parsed and executed. I've found people like to play around a bit and try things the tutorial doesn't specify, such as grepping a different part of the limerick or catting a different file.
I know it might be hard to implement but it's much more pleasing to have a more complete simulation - I got confused when I tried to grep 'yo-ho-ho' and just got the full limerick (though I haven't used grep much so I might be at fault here)
Good luck with it!