Back in 2003 I wrote my first high frequency trading system -- we used a mix of C and C#. Java was also a popular choice at that time.<p>Much has changed since then!<p>If you were building an order book or trading system today, what would be your goto language and why?
Golang. For performance with support for coroutines and garbage collection. The other choice would be C++ since tooling has improved greatly since 2003.