Langur is an open-source imperative/functional language. It deals with extremely large and small numbers natively using arbitrary-precision decimal floating point. Its principles of design are sensibility to humans, accuracy in calculation, and a clean, expressive syntax.
Influences include at least the following languages.
I initially developed langur following very useful books by Thorsten Ball (1, 2), but it has changed dramatically since.
I wrote a book explaining the design of some of langur's advanced features, in its stack-based virtual machine. See a free preview chapter at opcodebook.com.