Elements in `Reap` and `Sow`

Question

Can someone help explain it to me:

1. How does here e come out? Why b disappears?

   Reap[Sow[a]; b; Sow[c]; Sow[d]; e]
   

2. How does here 4 come out?

   Reap[Sow[1, x]; Sow[2, y]; Sow[3, x]; Sow[4, y], x]
   

Thanks a lot!

Answer 1

When you have a CompoundExpression the last expression is the result.

Look at the FullForm of the expression inside Reap:

FullForm[HoldForm[Sow[a]; b; Sow[c]; Sow[d]; e]]

In this case, the OutPut is just e, the last one. Now when you include the Reaping, you get things that are Sown in addition to e. Same explanation goes for the second one.