● Relocatable object file (.o file)○ Code and data that can be combined with other relocatable object files to form executable object file■ Each .o file is produced from exactly one source (.c) file● Executable object file (a.out file)○ Code and data that can be copied directly into memory and then executed● Shared object file (.so file)○ Special type of relocatable object file that can be loaded into memory and linked dynamically, at either load time or run-time

● Modularity○ Program can be written as a collection of smaller source files, rather than one monolithic mass.● Efficiency○ Time: Separate compilation■ Change one source file, compile, and then relink. No need to recompile other source files.○ Space: Libraries■ Common functions can be aggregated into a single file...

● Aggregates multiple independently compiled files containing machine code● Fills in those unknown addresses● The goal is to create 1 file with all of the needed code to run the program

○ This changes the format and structure of the code but preserves the semantics (what it does)○ Can change lots of details for optimization, as long as the overall effect is the same

● Processes #include, #define, #if, macros○ Combines main source file with headers (textually)○ Defines and expands macros (token-based shorthand)○ Conditionally removes parts of the code (e.g. specialize for Linux, Mac, ...)● Removes all comments

Four steps for C: preprocessing, compiling, assembling, linking

The type-fest package contains only types, meaning they are only used at compile-time and nothing is ever compiled into actual JavaScript code. This package contains functions that are compiled into JavaScript code and used at runtime.

If you rely on any external dependencies (files required in a preprocessor for example) you might want to watch these files for changes and re-run svelte compile. Webpack allows loader dependencies to trigger a recompile. svelte-loader exposes this API via options.externalDependencies.