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Lecture Programming languages (2/e): Chapter 12c - Tucker, Noonan

Chapter 12c - Ada. Ada was developed in the late 1970s by the Department of Defense for both large command and control systems, as weB as embedded, real-time systems. In the sections that follow, we use the name Ada to refer to the imperative subset of Ada. | Programming Languages 2nd edition Tucker and Noonan Chapter 12 Imperative Programming I really hate this darn machine; I wish they would sell it; It won’t do what I want it to, but only what I tell it. Programmer’s lament (anonymous) Contents 12.1 What Makes a Language Imperative? 12.2 Procedural Abstraction 12.3 Expressions and Assignment 12.4 Library Support for Data Structures 12.5 C 12.6 Ada 12.7 Perl 12.6 Ada developed in late 1970’s by DoD DoD spending billions of dollars on software over 450 languages in use solution: standardize on one language Higher Order Language Working Group Ada 83 problem: size of language/compiler no subsets rule hard times during 1990s use of COTS renewed interest COTS proved problematic development of Spark Ada NYU GNAT (Ada) compiler General Characteristics influencs: Algol, Pascal large language; case insensitive unlike C, array indexing errors trapped type safe generics exception handling -- strictly control type union = record case b : boolean of true : (i : integer); false : (r : real); end; var tagged : union; begin tagged := (b => false, r => 3.375); put(tagged.i); -- error generic type element is private; type list is array(natural range ) of element; with function ">"(a, b : element) return boolean; package sort_pck is procedure sort (in out a : list); end sort_pck; package sort_pck is procedure sort (in out a : list) is begin for i in a'first a'last - 1 loop for j in i+1 a'last loop if a(i) > a(j) then declare t : element; begin t := a(i); a(i) := a(j); a(j) := t; end; end if; Ex: Average comparable to C infinite loop; exit on end of file via exception inner loop to catch errors caused by non-numeric data wordy than C Ex: Matrix Multiplication overloaded * raises exception if the number of columns of A not equal to the number of rows of B a’first(2), a’last(2), a’range(2) compiler can verify at compile time that an indexing error cannot occur type Matrix is array (Positive range of Float, Positive range of . | Programming Languages 2nd edition Tucker and Noonan Chapter 12 Imperative Programming I really hate this darn machine; I wish they would sell it; It won’t do what I want it to, but only what I tell it. Programmer’s lament (anonymous) Contents 12.1 What Makes a Language Imperative? 12.2 Procedural Abstraction 12.3 Expressions and Assignment 12.4 Library Support for Data Structures 12.5 C 12.6 Ada 12.7 Perl 12.6 Ada developed in late 1970’s by DoD DoD spending billions of dollars on software over 450 languages in use solution: standardize on one language Higher Order Language Working Group Ada 83 problem: size of language/compiler no subsets rule hard times during 1990s use of COTS renewed interest COTS proved problematic development of Spark Ada NYU GNAT (Ada) compiler General Characteristics influencs: Algol, Pascal large language; case insensitive unlike C, array indexing errors trapped type safe generics exception handling -- strictly control type union = record case b : boolean of