This thesis represents the submission to the Open University for the degree of Master of Philosophy. The research topic lies within the discipline of computer science and in particular problems associated with the transportability of computer software are investigated. The study period was organised into 3 parts: - A literature search to look at what work had been done in the area. - The design of an intermediate language for a compiler. - The specification, design and implementation of a functional programming language in order to develop a portable programming environment. This thesis covers the work of the period Sep78 to Jun82, all of which was performed by part time study. The Thesis comprises 4 major sections and an appendix which shows program listings. The sections are as follows: - Section 1: The introduction - Section 2: The result of a literature search. - Section 3: A design for a compiler intermediate language, Ivor, covering the architecture of the underlying abstract machine and the structure of the intermediate language. - Section 4: The design and implementation of a function based programming language. Mule, including the structure of the language and a description of the implementation.