# Compilers: How To Make a Programming Language

Other compiler-related topics out of scope:
- What are programs anyway (Forth, LISP)
- Computation: Turing machines, lambda calculus
- Compiler optimization
- GC (motivated by LISP)

aesthetics:
- stay motivated; stick close to a c-like, imperative, procedural model because that's what people are used to

motivation / goals / what questions are we trying to answer:
- I want to be able to make a toy procedural language.
    - like C, Algol, JS, Lua, etc.
    - possible user motivations:
        - I want to make a game scripting language
        - I want to make a DSL for my job (and I want syntax highlighting!)
- I want to do simple static analysis of my projects

ok what do we want to cover
- classical compiler structure (lexer -> parser -> codegen)
- semantic analysis / type checking
- modern compiler structures (IR / SSA, optimization)
- interpreters vs. JITs vs. AOTs vs. "transpilers"
- executables and linkers
- regular expressions?
- regular languages / grammars / language structure / automata

the c compilation process
- translation units
- preprocessing -> (the whole compilation process) -> object files -> linking
- c compilation model is not in favor any more, don't like compiling all these files separately
- ABIs and FFI
- should maybe be in separate article

experts / consultants:
- Bill
- NeGate

## The actual progression

- Simple expression interpreter (parse and evaluate)
- Classical compiler construction (lex -> parse -> output), semantic analysis / type checking
    - motivation: complex structures! recursion! etc.
    - many of these resources exist and cover different aspects of the process in different ways
- Grammars and language structure
- Types of output (interpreter vs. AOT vs. JIT, etc.)
    - We can probably find resources on specific ones of these
- Modern phases (IR / SSA)
    - Mention WASM?
- The terrors of the real world
    - Executables, linkers, and debug info
    - The C ABI and FFI
    - Register allocation
- C is not the only language
    - LISP
    - Forth
    - This could be a whole topic maybe

## Link dump

- lua grammar: http://lua-users.org/wiki/LuaGrammar
- pascal railroad diagrams: https://www.cs.utexas.edu/users/novak/grammar.html
- tons of links: https://github.com/aalhour/awesome-compilers
- dragon book: http://ce.sharif.edu/courses/94-95/1/ce414-2/resources/root/Text%20Books/Compiler%20Design/Alfred%20V.%20Aho,%20Monica%20S.%20Lam,%20Ravi%20Sethi,%20Jeffrey%20D.%20Ullman-Compilers%20-%20Principles,%20Techniques,%20and%20Tools-Pearson_Addison%20Wesley%20(2006).pdf
- expression parsing examples:
    - pratt parsing and recursive descent: https://journal.stuffwithstuff.com/2011/03/19/pratt-parsers-expression-parsing-made-easy/
    - dunno, not recursive descent: https://www.cs.rochester.edu/u/nelson/courses/csc_173/grammars/parsing.html
- gary bernhardt's compiler from scratch: https://www.destroyallsoftware.com/screencasts/catalog/a-compiler-from-scratch
- lambda calculus interpreter: https://justine.lol/lambda/