1. A computer-implemented method for executing program code, the method comprising: receiving a source code file that includes computer code in a host language integrated with inset computer code in a domain specific language, the domain specific language being different from the host language; reading the source code file; responsive to reading computer code in the host language, invoking a set of computing instructions indicated by the computer code in accordance with the host language by interpreting a computing instruction indicated by the computer code as an operation in the host language; and responsive to reading inset computer code in the domain specific language, invoking a set of computing instructions indicated by the inset computer code in accordance with the domain specific language by performing operations including: selecting a domain specific language specification for the inset computer code, the domain specific language specification including instructions written in the host language for executing the inset computer code by relating tokens that include strings of characters from the domain specific language to corresponding tokens that include strings of characters from the host language and relating at least one grammatical rule for operations on tokens from the domain specific language to at least one corresponding grammatical rule for operations on tokens from the host language, and using the domain specific language specification to process the inset computer code.