interest computing for (h)ledger

 hledger-interest is a small command-line utility based on Simon Michael's
 hledger library. Its purpose is to compute interest for a given ledger
 account. Using command line flags, the program can be configured to use
 various schemes for day-counting, such as act/act, 30/360, 30E/360, and
 30/360isda. Furthermore, it supports a (small) number of interest schemes,
 i.e. annual interest with a fixed rate and the scheme mandated by the
 German BGB288 (Basiszins für Verbrauchergeschäfte). Extending support for
 other schemes is fairly easy, but currently requires changes to the source
 code.