8. A computer program product for executing program code, the computer program product comprising a computer-readable storage medium including computer program code that comprises: a host language processor configured to execute program code in a host language by interpreting a line of program code in the host language as an operation in the host language; a domain specific language inset processor configured to execute program code in a domain specific language by performing operations including: selecting a domain specific language specification for domain specific language, the domain specific language specification including instructions written in the host language for executing the program code in the domain specific language 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, the domain specific language being different from the host language, and using the domain specific language specification to process the inset computer code; and a lexical analyzer configured to receive a source code file that contains includes computer code in the host language integrated with inset computer code in the domain specific language, the lexical analyzer being further configured to pass program code in the host language to the host language processor and pass inset computer code in the domain specific language to the domain specific language inset processor.
8. A computer program product for executing program code, the computer program product comprising a computer-readable storage medium including computer program code that comprises: a host language processor configured to execute program code in a host language by interpreting a line of program code in the host language as an operation in the host language; a domain specific language inset processor configured to execute program code in a domain specific language by performing operations including: selecting a domain specific language specification for domain specific language, the domain specific language specification including instructions written in the host language for executing the program code in the domain specific language 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, the domain specific language being different from the host language, and using the domain specific language specification to process the inset computer code; and a lexical analyzer configured to receive a source code file that contains includes computer code in the host language integrated with inset computer code in the domain specific language, the lexical analyzer being further configured to pass program code in the host language to the host language processor and pass inset computer code in the domain specific language to the domain specific language inset processor. 9. The computer program product of claim 8 , wherein the lexical analyzer is further configured to detect the inset computer code using a predefined escape token.