Programming Languages

• — What is a programming language?
  • — Something between human language and machine language
  • — Programming language to human language is a set process
  • — Human language to programming language is art
• — What is machine language?
  • — CPU instructions are fixed size and binaries
  • — They are executed one after the other
  • — They decide on which circuits to use on which binary inputs
  • — Example instructions
    • — Load value from register
    • — Set value to registers
    • — Read value from memory (RAM) address
    • — Send value to I/O device
• — Obviously, it is difficult to code with machine language
• — How programming languages simplify over machine language?
  • — Use variable names to keep track of memory addresses
  • — Make high level data structures and functions that are deterministically transformed to machien instructions
    • — Examples
      • — if condition is basically severl machine instructions
        • — calculate this boolean value to this meorty address
        • — if true jump to this memory address
        • — if false jump to this memory address
        • — in the end of true and false part, jump to the outter address
  • — Allows for evolving layers of abstraction
• — How different programming languages are possible? What support does operating system give?
  • — There are ways to invoke OS functions
    • — A C program, can get C libraries that operating system allows
      • — Create things on heap
      • — Read/write from file
      • — Spawn and talk to other processes
    • — Other compilers also turn to programs to machine code
    • — Interpreters are native programms, that read code from source language to
• — Compiling
  • — Turn to machine instructions
  • — Different for different CPU/Operating System combinations
  • — Once compiled, thigns are fast
• — Intrepretors
  • — There is a runtime that is a native program which read the code and decides what to do
    • — Read teh code and add things to heap memory
• — Different types of programming languages
  • — Sequential/Scripting languages
    • — Basic data structures
    • — All about if-then, while/for loops, functions
  • — Object oriented
    • — Objects are data and functions that are in the heap with a lot of connections
    • — Template approach when there is a lot of sharing involved
  • — Functional
    • — Less computer hardware and more mathematical
    • — Description of data and process
    • — Compiler/runtime takes care of turning that to steps
• — What makes a programming language fast?
• — What makes a programming language easy to read?
• — Features
  • — if/then
  • — while
  • — functions
  • — error handling
  • — Type System
  • — Functons as values
  • — Monads
    • — For async
    • — For error handling