The fair value of the loan for the lender will be arrived by discounting the future cash inflows at market rate of interest which will be below 100. Assume that it is 90. So Lender will debit Loan receivable with 90 , book impairment loss of 10 in P&L and credit cash with 100. Subsequent to this, the loan of 90 will be unwind by booking an interest income in P&L and giving a debit to the loan receivable. This will continue as long as the loan of 90 becomes 100 on the date of redemption (at a future date).
Receiver will mirror the above entries by booking a gain of 10 in PL on initial recognition. Subsequent to this, he needs to book an interest expense on this loan.
Hope it is clear to you.