Whiley is a general purpose multi-paradigm, compiled language developed by David Pearce. The language combines features from the Functional and Imperative paradigms, is statically typed and supports formal specification through function preconditions, postconditions and loop invariants. The language is also notable for the use of flow-sensitive typing, also known as "flow typing". The Whiley project began in 2009 in response to the "Verifying Compiler Grand Challenge" put forward by Tony Hoare in 2003. The first public release of Whiley was made in June, 2010.