1. Reasons To Study Programming Languages
Increased capacity to express programming concepts
Improved background for choosing appropriate languages
Increased ability to learn new languages
Understanding the significance of implementation

2. Programming Domains Scientific applications Business applications
Artificial intelligence
Systems programming
Scripting languages
Special purpose languages

3. Language Evaluation Criteria: Readability
Considered to be the most important criteria
Factors
Overall simplicity
Too many features is bad
Multiplicity (more than one way to accomplish a particular operation) of features is bad

4. Language Evaluation Criteria: Readability
Factors:
Orthogonality (Orthogonality refers to the ability of a certain language feature to function the same in different contexts)
Makes the language easy to learn and read
Meaning is context independent

5. Language Evaluation Criteria: Readability
Factors:
Control statements
remember goto’s?
Data type and structures
boolean as an int
Syntax considerations
Length of identifiers, reserved words

6. Language Evaluation Criteria: Writability
Factors:
Simplicity and orthogonality
Smaller and more context free is generally better
Support for abstraction
Ability to define your own data types and operations
Expressivity

7. Language Evaluation Criteria: Reliability
Factors:
Type checking
Compile Time versus Run Time
Exception handling
Aliasing
Can be dangerous
Readability and writability

8. Language Evaluation Criteria: Cost
Categories:
Programmer training
Software creation
Compilation
Execution
Compiler cost
Poor reliability
Maintenance

9. Language Evaluation Criteria: Other
Portability
Generality
Well-definedness

10. Von Neumann Architecture
Data and Instructions are stored in the RAM
Instructions must be transferred from the RAM to the CPU
Results of the computation must be moved back from the CPU to RAM
Regardless of how fast CPU gets the speed of the program is very heavily influenced by the speed of the I/O system (system bus)

11. Primary Influences On Language Design
Computer architecture
We use imperative languages, at least in part, because we use von Neumann machines
Programming methodologies
1950s and early 1960s: Simple applications; worry about machine efficiency
Late 1960s: People efficiency became important; readability, better control structures
Late 1970s: Data abstraction
Middle 1980s: Object-oriented programming

12. Language Categories Imperative
Relies on state changes to accomplish results
Most common categories are procedural and object-oriented
Functional
Applying functions to the parameters
Logic
Uses set of rules to get the results

13. Language Design Trade-Offs
Reliability versus cost of execution
Writability versus readability
Flexibility versus safety

14. Implementation Methods
Compilation
Translate high-level program to machine code
Slow translation
Fast execution
Pure interpretation
No translation
Slow execution

15. Implementation Methods
Hybrid implementation systems
Small translation cost
Medium execution speed
Ex. Java source code is being first compiled into the bytecode, which can be thought as a machine-independent assembly language. The JVM interprets the bytecode similarly to the way CPU interprets machine language instructions. Many techniques exist to optimize the execution of the bytecode including JIT and HotSpot