CSCI 1302

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CSCI 1302

• History and Overview of Programming Languages

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Evolution

• You know about op-codes
• Fun?
• Not human-friendly
• Open to errors
• Move towards a more human-centered endeavor
• Assembly languages a first start

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From Op-Codes to Assembly

• 156C
• 166D
• 5056
• 306E
• C000

• LD R5, Price
• LD R6, ShippingCharge
• ADDI R0, R5 R6
• ST R0, TotalCost
• HLT

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Problems with 2nd Generation Language (Assembly)

• Machine specific
• Still low-level processing
• Hex to instruction
• Memory address to variable identifier
• Need more abstraction

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3rd Generation Languages

• Specific to task
• Mathematical (FORTRAN)
• List Processing AI (Lisp)
• Systems (C)
• Business Logic (COBOL)
• Translated/compiled into machine-level
  instructions
• Alternatively interpreted JIT
• Machine independence portability available

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Software Development Paradigms
Machine-centric
Human-centric
Lisp
Functional
C
C
Machine Languages
Object-oriented
C
ImperativeProcedural
Prolog
Declarative
1960
1970
1980
1990
2000
1950
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Imperative/Procedural

• Given problem
• Derive algorithm to solve problem
• Implement algorithm as series of commands
  (imperatives)
• Modularity and abstraction critical
• Handle scope
• Manage complexity of instructions and data

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Declarative

• Describe/declare the problem
• Language system provides general-purpose
  problem-solving algorithm
• Enter problem statement
• Solution(s) derived
• Example
• Horses run fast
• Jack is a horse
• Jack runs fast - TRUE

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Functional

• Given primitives of the language
• Define small functions that accept input and
  generate output
• Chain small functions together to generate
  complex solutions
• Nested complexities
• Examples
• (Divide (Sum Numbers) (Count Numbers))
• (First (Sort Numbers))

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Object-Oriented

• Collection of data methods that act on the data
• Message passing
• Inheritance
• Collaborative and large-scale software
  development
• Combination of imperative units

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Primitives of Languages

• Data types
• Variables (instances of types)
• Data structures (heterogeneous and homogeneous
  collections)
• Constants
• Assignment
• Control statements (goto, if-then, loop)
• Comments (for the humans)

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Primitives of Languages (cont)

• Procedures (modular abstraction)
• Functions (return/resolve-to-a value)
• Parameter passing
• By reference by value
• Actual formal
• Input/Output

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Translation Process

• Begin with source (your code)
• Lexical Analysis (tokenize)
• Parsing (conform to valid syntax) into statements
• Code generation into machine-level instructions
• End with object program

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Program Preparation

• Begin with object program
• Link (establishes connections between object
  programs) generates load module
• Loader (take load module into memory and execute
  program)

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CSCI 1302

• Declarative Programming and Prolog

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Assumptions

• General problem-solving algorithm
• Formal logic rules
• AND
• OR
• NOT
• IMPLIES
• Seek resolution

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Logical Deduction Examples

• A Kermit is a prince
• B Miss Piggy is an actress
• A or B
• B and not A
• A -gt B

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Determining Resolvents

• Given
• P or Q
• R or not Q
• Conclude
• P or R

P or Q
R or not Q
P or R
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Determining Resolvents (cont)

• Given
• P or Q
• R or not Q
• not R
• Conclude
• P

P or Q
R or not Q
not R
P or R
P
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Clause Form

• Expressed as two elementary components connected
  via a boolean OR
• P or Q
• P -gt Q
• Translates to Q or not P
• P and Q
• Translates to

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FIN