1. A computer-implemented method comprising: locating a string representation of an expression, the string representation of the expression including an identification of a programming language associated with the expression, the string representation of the expression to be converted into the expression based on the programming language, wherein the string representation of the expression is defined in a meta-object model of an application; accessing a data type definition corresponding to the programming language, the data type definition including a converter for converting the string representation of the expression into the expression, wherein the converter is further configured to convert a string representation of a numerical value into a corresponding numerical value that can be processed by a computer system during runtime, and wherein the converter is part of the meta-object model; and generating an executable runtime representation of the expression.