A tiny cross-comparison of code executors and translators for educational purposes.
The purpose of this repo is to disambiguate via concrete code examples the following concepts:
- Interpretation
- JIT compilation
- Standard compilation
- Optimizing compilation
This demo uses an invented, trivial, toy language "GScript" which builds up and/or prints a stateful string. It is not intended to be a realistic language, nor are the implementations of these scripts intended to illustrate viable or recommendable techniques for real languages. In particular, compilers typically lex, parse, and generate code according to formal grammars. The compilers shown here on the other hand are practically primordial in their lack of sophistication.
In the src folder are several files:
| Filename | Type | Purpose |
|---|---|---|
hello-world.gs |
GScript Program | Source code |
hello-broken.gs |
GScript Program | (Incorrect) Source code |
01-interpreter.js |
Interpreter | Reads & executes source code |
02-jit.js |
Just-in-Time (JIT) Compiler | Translates source to JS & runs result |
03-compiler.js |
Compiler | Translates source to JS & saves result |
04-opt-compiler.js |
Optimizing Compiler | Translates source, simplifies, & saves result |
cs src
node 01-interpreter.js # runs the interpreter
node 02-jit.js # runs the JIT
node 03-compiler.js # runs the compiler
node hello-world.js # runs the compiled program
node 04-opt-compiler.js # runs the optimizing compiler
node hello-world.js # runs the compiled & optimized programRead the code, understand how it works, and see the difference in how the final result is produced. There is also a deliberately broken source GS file (hello-broken.gs); try changing the files to load that source code. How do the different modules behave when given incorrect code? (Hint: the interpreter fails in a different way than the compilers do.)
- A GScript program manipulates and/or prints a single stateful string value.
- Blank lines are ignored.
- Any line beginning with
#is a comment. - One statement per line, three kinds of statements:
+adds any following characters to the string.-Nremoves the last N characters from the string.print(or any line beginning withp) prints the current string state.