Q (programming language from Kx Systems)

Q is a programming language for array processing, developed by Arthur Whitney. It is proprietary software, commercialized by Kx Systems. Q serves as the query language for kdb+, a disk based and in-memory, column-based database. Kdb+ is based on the language k, a terse variant of the language APL. Q is a thin wrapper around k, providing a more readable, English-like interface. One of the use cases is financial time series analysis, as one could do inexact time matches. An example is to match the a bid and the ask before that. Both timestamps slightly differ and are matched anyway.