CS 4337 Midterm - Chapters 1-4

What three broad categories of language are listed in the course?

Natural human languages, constructed human languages, and programming languages.

How do syntax and semantics differ?

Syntax = structure; semantics = meaning. Together they define a language.

What is a lexicon, and how does it differ from an alphabet?

Lexicon = vocabulary. Alphabet = symbols used to form strings.

What is the intended difference between ambiguity in natural and programming languages?

Natural language often permits ambiguity; programming languages aim for precise, unambiguous interpretations.

Who is Noam Chomsky in the course's language history?

A linguist associated with formal grammars, including context-free grammars.

What are John Backus's major contributions discussed in class?

Led FORTRAN development and introduced the notation that became BNF.

Why study programming-language concepts?

Express ideas, choose and learn languages, understand implementation, use familiar languages better, and advance computing.

Why are there many programming languages instead of one universal best language?

Different domains require different trade-offs in readability, writability, reliability, efficiency, and cost.

What characterizes scientific applications, and which language is the classic example?

Floating-point calculations and arrays; FORTRAN (Formula Translating).

What characterizes business applications, and which language is the classic example?

Reports, decimal data, characters, and records; COBOL (Common Business Oriented Language).

What characterizes the traditional AI domain in the slides?

Symbolic processing and linked lists; Lisp and Prolog.

What characterizes systems programming, and which language is emphasized?

Efficient execution and low-level control; C.

What kinds of languages appear in web software?

Markup (HTML), scripting (PHP/JavaScript), and general purpose languages (Java).

What is an embedded system?

Software built into a device for a dedicated purpose, such as an appliance controller.

How does gaming differ from offline 3-D graphics and animation?

Gaming renders and responds to input in real time; offline animation lacks that immediate interaction requirement. Gaming examples: C++, C#.

What four main criteria evaluate a programming language?

Readability, writability, reliability, and total cost.

What is readability, and why does it matter?

Ease of understanding programs; it affects maintenance and error detection.

What is writability?

Ease of writing programs for a particular problem domain.

What is reliability?

Conformance to specifications under intended operating conditions.

What costs belong in a language's total cost?

Training, development, compilation, execution, tools, failures, and maintenance; portability and generality also affect cost.

How can simplicity improve readability, and when can it hurt?

Fewer features ease learning, but overly primitive constructs can make it hard to read

What is feature multiplicity?

Multiple ways to perform one operation

What is operator overloading?

One operator symbol has multiple meanings or operand types. Surprising uses can reduce readability.

What is orthogonality in language design?

A small set of constructs combines consistently, with few special cases.

Why do suitable data types and clear syntax improve readability?

They express intent directly: timeout = true is clearer than timeout = 1.

What is abstraction?

Using complex operations or structures while hiding unnecessary details.

How do process abstraction and data abstraction differ?

Process abstraction hides an operation behind a subprogram; data abstraction hides a representation behind an interface.

What is type checking?

Detecting type errors at compile time or run time.

According to the sample quiz, what makes a language strongly typed?

All type errors are detected at compile time or run time. Strong typing differs from static typing.

When are types determined or checked in dynamic versus static typing?

Dynamic typing: during execution. Static typing: before execution, usually during compilation.

What is exception handling, and how does it support reliability?

Detecting and handling run-time errors to enable recovery or controlled termination.

What is aliasing?

Multiple names or reference paths refer to the same storage location.

Do equal values imply aliasing?

No. Aliasing requires shared storage, not just equal values.

What two major influences shape language design?

Computer architecture and programming methodology.

How does the von Neumann architecture influence imperative languages?

Variables model memory cells, assignments update stored values, and iteration fits repeated instruction execution.

What is the von Neumann bottleneck?

Limited transfer speed between memory and CPU constrains execution.

What distinguishes imperative and procedural programming?

Imperative programming updates state through commands; procedural programming organizes those commands into subroutines.

What distinguishes functional programming?

Computation applies functions. Pure functional programming avoids mutable state and uses recursion and conditional expressions.

What does it mean that functions are first-class entities?

Functions can be stored, passed as arguments, and returned as values.

What distinguishes logic programming?

Facts and rules are used to infer answers to queries; Prolog is the main example.

How do declarative and imperative programming differ?

Declarative: specify desired results. Imperative: specify state changing steps. Functional and logic programming are declarative.

What features characterize object-oriented programming in the slides?

Data abstraction, inheritance, and polymorphism.

What is a markup/programming hybrid?

Markup extended with programming constructs, such as selection and iteration; examples include XSLT and JSP/JSTL.

Give the three language-design trade-offs emphasized in class.

Reliability vs. execution cost; readability vs. writability; flexibility vs. reliability.

What does a compiler do?

Translates source into another representation, typically machine code in the basic compilation model.

What does a pure interpreter do?

Executes source operations at run time without first producing a separate native executable.

What is a hybrid implementation?

Translates source to intermediate code, then executes it with an interpreter and/or JIT compiler.

What is just-in-time (JIT) compilation?

Compiles intermediate code into machine code during execution, often when a method is needed.

Why can Java bytecode support portability?

The same bytecode can run on any system with a compatible JVM and run-time support.

What language does a CPU execute directly?

Its architecture's machine language.

Why do programmers generally prefer high-level languages to machine code or assembly?

Easier development, understanding, modification, and often portability; faster execution is not guaranteed.

What are the main compilation phases and their jobs?

Lexical: characters to tokens. Syntax: tokens to parse structure. Semantic: check constraints. Code generation: produce executable code.

What is linking?

Combining compiled program units and required libraries into an executable.

What is a preprocessor?

Transforms source before compilation, such as expanding C #include and #define.

Why was early machine-code programming difficult?

It was tedious, error-prone, hard to read/modify, and lacked convenient tools and expressions.

What were Short Code and Speedcoding intended to improve?

Higher-level pseudocode eased programming; Speedcoding added arithmetic, branching, and array support at a speed/memory cost.

Why was efficient compilation central to FORTRAN's success?

Scientific users prioritized machine efficiency; fast compiled code made a high-level language practical.

What early FORTRAN features are emphasized in the slides?

Counted loops, arrays, subprograms, formatted I/O, and three-way arithmetic IF.

How did implicit typing work in early FORTRAN?

Initial I, J, K, L, M, or N implied integer; other initials implied floating-point.

How did FORTRAN develop beyond its earliest implementation?

Separate compilation, explicit types, improved control/strings, modules, dynamic arrays, pointers, recursion, OOP, and parallelism.

What does Lisp stand for, who designed it, and what problem domain motivated it?

LISt Processing; John McCarthy; AI and symbolic computation.

What are Lisp's two fundamental data categories in the slides?

Atoms and lists, including nested lists.

What computational ideas did Lisp pioneer?

Functional programming, recursion, conditional expressions, and garbage collection.

How do Scheme and Common Lisp differ in the slides?

Scheme: small, statically scoped, first-class functions. Common Lisp: larger and combines many dialect features.

What is distinctive about Scala in the course?

Functional support, a strong type system rooted at Any, and JVM execution.

What problem was ALGOL designed to address?

A machine-independent language and common notation for publishing algorithms.

What major ALGOL contributions are emphasized?

Local block scope, recursion, stack-dynamic arrays, machine independence, and syntax formally defined with BNF.

Why was ALGOL influential despite limited adoption?

It standardized algorithm publication and influenced imperative languages. Adoption suffered from implementation issues and established competitors.

What is a block's role in ALGOL-style languages?

Groups declarations and statements and can establish local scope.

What design philosophy characterized the later orthogonal ALGOL design?

A few basic concepts with consistent combinations; contributions included user defined structures, references, and dynamic arrays.

What design goals and features distinguish COBOL?

English-like business programming with long names, hierarchical records, and a separate data division.

Which earlier language influenced COBOL?

FLOW-MATIC, an English-like data-processing language separating data from code.

What language was designed for beginners and became closely associated with timesharing?

BASIC, by John Kemeny and Thomas Kurtz, designed for easy learning and quick turnaround.

What does BASIC stand for?

Beginner's All-purpose Symbolic Instruction Code.

What was PL/I intended to combine?

Scientific and business computing in one language.

What contributions and drawback are associated with PL/I?

Concurrency, exceptions, pointers, and array cross sections; its size and some feature designs made it complex.

What did APL and SNOBOL have in common?

Dynamic typing and storage allocation: assigned values determine types, and storage can be allocated at assignment.

What distinguishes APL from SNOBOL?

APL: powerful scalar/array operations. SNOBOL: string manipulation and pattern matching.

What did SIMULA contribute to programming languages?

Classes, objects, inheritance, and coroutines, originally for system simulation.

What was Pascal primarily designed for?

Teaching structured programming; designed by Niklaus Wirth.

What are C's origin, purpose, and key trade-off in the slides?

Dennis Ritchie at Bell Labs; systems programming. Powerful low-level control, but comparatively weak type checking.

What distinguishes Prolog from a conventional procedural language?

It uses logic and inference over facts/rules instead of explicitly listing procedural steps.

What application area motivated Ada, and what major facilities did it provide?

Embedded and real time systems; packages, exceptions, generics, and concurrency through tasking.

Who is Ada Lovelace in the course's history?

Wrote an algorithm for Babbage's Analytical Engine; recognized as the first programmer and Ada's namesake.

Why is Smalltalk important in object-oriented language history?

An early full OOP language with abstraction, inheritance, and dynamic binding; also influential in GUI development.

How did C++ combine earlier language ideas?

Stroustrup combined C style procedural programming with SIMULA influenced OOP, increasing language complexity.

How do Objective-C and Delphi relate to earlier languages?

Objective-C: C plus Smalltalk-inspired OOP. Delphi: Pascal plus OOP.

What safety and portability choices distinguish Java from C++ in the slides?

Managed references, garbage collection, JVM bytecode, no explicit pointer arithmetic or manual memory deallocation.

What tasks made Perl prominent in the course's web history?

Text processing, CGI programming, and UNIX administration; variable prefixes distinguish scalar, array, and hash namespaces.

What is JavaScript's traditional web role, and how is it related to Java?

Client-side scripting for dynamic web pages. It is a separate language, not a Java dialect.

What is PHP's traditional web role?

Server-side web scripting for forms and database access; PHP means PHP: Hypertext Preprocessor.

What features characterize Python in the slides?

Object-oriented scripting, dynamic typing with type checking, and lists, tuples, and dictionaries.

What features characterize Ruby in the slides?

Matsumoto's object-oriented scripting language: all data are objects, and many operators are redefinable methods.

Which language is presented as the flagship .NET language?

C#, influenced by C++, Java, and Delphi, with delegates, properties, enums, and anonymous types.

What are XML and XSLT?

XML defines structured markup; XSLT transforms XML and includes programming constructs.

What are JSP and JSTL?

JSP supports dynamic web documents; JSTL supplies reusable tags for tasks such as loops and conditionals.

What is a language in formal-language terminology?

A set of sentences formed over an alphabet.

What is a lexeme?

An actual lowest-level syntactic unit, such as sum, 17, +, or if.

What is a token?

A category of lexemes, such as identifier or integer literal.

When does a lexeme match a token?

When its characters match the token category's pattern.