"First book-length exposition of the denotational (or `mathematical" or `functional") approach to the formal semantics of programming languages (in contrast to `operational" and `axiomatic" approaches). Treats various kinds of languages, beginning with the pure-lambda-calculus and progressing through languages with states, commands, jumps, and assignments. This somewhat discursive account is a valuable compilation of results not otherwise available in a single source."-- American Mathematical Monthly