static Func<int, int> ChooseOperation(ITalkToUser ui)
{
var operation = ui.Ask("choose operation");
if( operation == "syracuse" )
{
var rank = int.Parse(ui.Ask("rank"));
return i => SyracuseSequence(i).ElementAt(rank-1);
}
else if( operation == "integer sum" )
{
return i => i*(i+1)/2;
}
else
{
return i => i*i;
}
}
static Func<IEnumerable<int>, IEnumerable<int>> ChooseFilter(ITalkToUser ui)
{
var filter = ui.Ask("choose filter");
if( filter == "odd under" )
{
var maxValue = int.Parse(ui.Ask("max value"));
return e => e.TakeWhile( n => n <= maxValue ).Where( n => n%2==1 );
}
else if( filter == "under" )
{
var maxValue = int.Parse(ui.Ask("max value"));
return e => e.TakeWhile( n => n <= maxValue );
}
else
{
var numberOfItems = int.Parse(ui.Ask("number of items"));
return e => e.Take(numberOfItems);
}
}