Structure and Interpretation of Computer Programs - 2nd Edition (MIT Electrical Engineering and Computer Science)
Harold Abelson, Gerald Jay Sussman, Julie Sussman
Language: English
Pages: 683
ISBN: 0262510871
Format: PDF / Kindle (mobi) / ePub
Structure and Interpretation of Computer Programs has had a dramatic impact on computer science curricula over the past decade. This long-awaited revision contains changes throughout the text. There are new implementations of most of the major programming systems in the book, including the interpreters and compilers, and the authors have incorporated many small changes that reflect their experience teaching the course at MIT since the first edition was published. A new theme has been introduced that emphasizes the central role played by different approaches to dealing with time in computational models: objects with state, concurrent programming, functional programming and lazy evaluation, and nondeterministic programming. There are new example sections on higher-order procedures in graphics and on applications of stream processing in numerical programming, and many new exercises. In addition, all the programs have been reworked to run in any Scheme implementation that adheres to the IEEE standard.
expressions to be evaluated in environments are reduced to procedures to be applied to arguments, which in turn are reduced to new expressions to be evaluated in new environments, and so on, until we get down to symbols, whose values are looked up in the environment, and to primitive procedures, which are applied directly (see figure 4.1).4 This evaluation cycle will be embodied by the interplay between the two critical procedures in the evaluator, eval and apply, which are described in
procedures into two kinds: It calls apply-primitive-procedure to apply primitives; it applies compound procedures by sequentially evaluating the expressions that make up the body of the procedure. The environment for the evaluation of the body of a compound procedure is constructed by extending the base environment carried by the procedure to include a frame that binds the parameters of the procedure to the arguments to which the procedure is to be applied. Here is the definition of apply:
continuation that will intercept a subsequent failure; whatever failure would otherwise have called fail2 calls this procedure instead, to undo the assignment before actually calling fail2. (define (analyze-assignment exp) (let ((var (assignment-variable exp)) (vproc (analyze (assignment-value exp)))) (lambda (env succeed fail) (vproc env (lambda (val fail2) ; *1* (let ((old-value (lookup-variable-value var env))) (set-variable-value! var val env) (succeed 'ok (lambda () ; *2*
of growth of encoding [2] Huffman, David insert! Hughes, R. J. M. in one-dimensional table in two-dimensional table insert-queue!, [2] IBM 704 install-complex-package identity install-polar-package install-polynomial-package if (special form) install-rational-package cond vs. install-rectangular-package evaluation of install-scheme-number-package normal-order evaluation of instantiate one-armed (without alternative) instantiate a pattern predicate, consequent, and
with how a computational object can change and yet maintain its identity. This will force us to abandon our old substitution model of computation (section 1.1.5) in favor of a more mechanistic but less theoretically tractable environment model of computation. The difficulties of dealing with objects, change, and identity are a fundamental consequence of the need to grapple with time in our computational models. These difficulties become even greater when we allow the possibility of