A common attraction to functional programming is the ease with which proofs can be given of program properties. A common disappointment with functional programming is the difficulty of expressing input/output (I/O), while at the same time being able to verify programs. Here, the author shows how a theory of functional programming can be smoothly extended to admit both an operational semantics for functional I/O and verification of programs engaged in I/O. He obtains operational semantics for the three most widely implemented I/O mechanisms for lazy languages, and proves that the three are equivalent in expressive power. He develops semantics for a form of monadic I/O and verifies a simple programming example. These theories of functional I/O are based on an entirely operational theory of functional programming, developed using Abramsky’s ‘applicative bisimulation’.
• First ever semantics of the three most widely implemented I/O mechanisms in lazy functional languages • Novel material on ‘applicative bisimulation’ • Treats monadic denotational semantics for first time in book form
Contents
Preface; 1. Introduction; 2. A calculus of recursive types; 3. A metalanguage for semantics; 4. Operational precongruence; 5. Theory of the metalanguage; 6. An operational theory of functional programming; 7. Four mechanisms for teletype I/O; 8. Monadic I/O; 9. Conclusion; Bibliography; Notation; Index.
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