PPT-cs784(TK)

Author : ellena-manuel | Published Date : 2016-12-06

1 Semantics of Procedures and Scopes Kinds of Scope Static or Lexical scope determined by structure of program Scheme C Java and many compiled languages Dynamic

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cs784(TK): Transcript

1 Semantics of Procedures and Scopes Kinds of Scope Static or Lexical scope determined by structure of program Scheme C Java and many compiled languages Dynamic scope determined by path of execution. CS784: Programming Languages. Prabhaker Mateti. Study …. EOPL3 . Chapter 3: 3.1, 3.2. source code: chapter3/let-. lang. /*. 1722 data-. structures.scm. 4415 . drscheme-init.scm. 1450 . environments.scm. Prabhaker. . Mateti. ACK: Assembled from many sources. About Attribute Grammars. Attribute grammars (AGs) add semantic info on parse tree nodes . Used for semantic checking and other compile-time analyses, e.g., type checking in a compiler. Dijkstra’s Predicate Transformer. s. Axiomatic Semantics. gcd. -lcm algorithm w/ invariant. {PRE: (x = n) and (y = m)}. u := x; v := y;. while . {INV: 2*m*n = x*v + y*u}. (x <> y) do. if x > y then. 1. Specification and Implementation of Abstract Data Types. Spec v. Impl. (Functional) Specs should describe behavioral aspects only. Should ignore performance details. A “suitable implementation” requires client specific issues and trade-offs.. More on Evaluations. CS784(pm). 1. Scheme Expressions. Constants: numbers, . booleans. .. Variables: names for values. Created using the special form . define. Special. forms have special rules for evaluation. . Procs. w/. Params. EOPL3 Chapter 4. Expressible vs. Denotable values. Expressible Values . the language can express and compute these. represented in the language's syntax as expressions. Denotable Values . Procs. w/. Params. cs784(tk) . 1. Assignment, LHS := RHS. l-value: left-, location, address, reference, …. r-value: right-, . int. , real, address, …. env. and store allow one to describe the semantics of assignment in a purely functional style. (DENOTATIONAL SEMANTICS). Different Levels of Syntax. Lexical syntax. Basic symbols (names, values, operators, etc.). Concrete syntax. Rules for writing expressions, statements, programs. Input to compilers/interpreters. Abstract syntax. 1. Implementing Recursion. Recap: Goals. Experimenting with PL design alternatives Scoping, parameter passing, arrays, .... Runnable. prototype of reference implementation.. Cf. Informal description of a programming problem with an example executable for reference.. EOPL3 Sections . 3.4 - 3.7. The LETREC Language. All of PROC, plus …. Concrete:. Expression :: = . letrec Identiﬁer (Identiﬁer) = . Expression in Expression. AST:. letrec-exp (proc-name bound-var.

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