Programming and programming languages

Procedural (imperative) high level languages

• program: sequence of instructions (e.g. Fortran, Cobol, Algol, Pascal, C)
• assignment statement
• control structures (for the control of sequential execution, branching and cycling)
• programmer’s role ⇒ “what” and “how”
  • to describe what is to be calculated
  • to organize the calculation
  • to organize memory management
• assignment instruction is said to be dangerous in high-level languages, just as the GO TO instruction was considered dangerous for structured programming in the '68s

Declarative (descriptive, applied) very high level languages

• based on expressions
• expressive, easy to understand (have a simple basis), extensible
• program: descriptions that state information about values, rather than instructions to determine values or effects
• programmer’s role ⇒ “what” (NOT “how”)
• two classes of declarative languages
  • functional languages (e.g. Lisp, ML, Scheme, Haskell, Erlang)
    • focus on values of data described by expressions (built through applications of functions and definitions of functions), with automatic evaluation of expressions
  • logical languages (e.g. Prolog, Datalog, Parlog)
    • focus on logical assertions that describe the relationships between data values and automatic derivations of answers to questions, starting from these assertions
• have applications in Artificial Intelligence for automated proofs, natural language processing and speech understanding, expert systems, machine learning, intelligent agents, etc.

Multiparadigm languages: F#, Python, Scala(imperative, functional, object oriented)

Interactions between declarative and imperative languages -declarative languages that provide interfaces with imperative languages (eg C, Java): SWIProlog, GNUProlog, etc.

Logtalk: integrates logic and object-oriented programming