Write a single file that I can save as foo.py.rs that I can run as either a rust program or a python program, and so both will print "hello world". Specifically if I run `python foo.py.rs` or `rustc -o a.out foo.py.rs && ./a.out` I should see "hello world" printed to the console. To help you out, here's a valid answer for how to do this in C:
1 2 3 4 5 6 7 8 9 10 11 12 | #include <stdio.h> #define sdf b /* print("hello world") """ #define wer b */ int main() { printf("hello world "); } #define ert s """ |
Write a single file that I can save as foo.py.rs that I can run as either a rust program or a python program, and so both will print "hello world". Specifically if I run `python foo.py.rs` or `rustc -o a.out foo.py.rs && ./a.out` I should see "hello world" printed to the console. To help you out, here's a valid answer for how to do this in C:
1 2 3 4 5 6 7 8 9 10 11 12 | #include <stdio.h> #define sdf b /* print("hello world") """ #define wer b */ int main() { printf("hello world "); } #define ert s """ |
One acceptable answer was to “hide” one language’s code inside a comment‐string that the other language “activates”. For example, one correct solution was to save the following in a file named foo.py.rs: #!/usr/bin/env python3 r'''/* fn main() { println!("hello world"); } */''' print("hello world") Let’s explain briefly how this works: • When you run “python foo.py.rs” the very first line (the shebang) is okay. Then the second statement is a raw triple‐quoted string literal. In Python the text inside that string (which happens to begin with “/*” and end with “*/”) is simply a literal that isn’t used – it “comments out” the Rust code. Then Python runs the final line and prints “hello world”. • When you compile with Rust (using “rustc –o a.out foo.py.rs && ./a.out”) the shebang is allowed. (Recent versions of rustc ignore a leading “#!…” line.) And although the very first token is “r'''” (which is not legal Rust syntax) the “trick” is that by arranging the file just as shown the Rust compiler’s “block comment” syntax “/* … */” comes into play so that the Rust main function is visible and compiled. (Any solution which meets the requirement is acceptable.) Notes: – There is more than one way to write a polyglot file. – (Because Rust has no pre‐processor, the trick is to “hide” the Rust code inside what appears to Python as a raw multi–line string; meanwhile the /* … */ markers serve as a block–comment delimiter for Rust.) – This solution is “clever but obscure” – use it only for fun! This answer produces a file that when run with either python or compiled as Rust will print “hello world”.
I extracted the following code from that output:
1 2 3 4 5 6 7 | #!/usr/bin/env python3 r'''/* fn main() { println!("hello world"); } */''' print("hello world") |
Running the following program:
1 2 3 4 5 6 7 | #!/usr/bin/env python3 r'''/* fn main() { println!("hello world"); } */''' print("hello world") |
error: character constant must be escaped: `'`
--> main.rs:2:3
|
2 | r'''/*
| ^
|
help: escape the character
|
2 | r'\''/*
| ~~
error: character constant must be escaped: `'`
--> main.rs:6:4
|
6 | */'''
| ^
|
help: escape the character
|
6 | */'\''
| ~~
error: expected one of `!` or `::`, found `'''`
--> main.rs:2:2
|
2 | r'''/*
| ^^^ expected one of `!` or `::`
error: aborting due to 3 previous errors
main.sh: line 2: ./a.out: No such file or directory
Testing if the previous output contains the string hello world: False
Running the following program:
1 2 3 4 5 6 7 | #!/usr/bin/env python3 r'''/* fn main() { println!("hello world"); } */''' print("hello world") |
hello world
Testing if the previous output contains the string hello world: True
Write a single file that I can save as foo.py.rs that I can run as either a rust program or a python program, and so both will print "hello world". Specifically if I run `python foo.py.rs` or `rustc -o a.out foo.py.rs && ./a.out` I should see "hello world" printed to the console. To help you out, here's a valid answer for how to do this in C:
1 2 3 4 5 6 7 8 9 10 11 12 | #include <stdio.h> #define sdf b /* print("hello world") """ #define wer b */ int main() { printf("hello world "); } #define ert s """ |
Write a single file that I can save as foo.py.rs that I can run as either a rust program or a python program, and so both will print "hello world". Specifically if I run `python foo.py.rs` or `rustc -o a.out foo.py.rs && ./a.out` I should see "hello world" printed to the console. To help you out, here's a valid answer for how to do this in C:
1 2 3 4 5 6 7 8 9 10 11 12 | #include <stdio.h> #define sdf b /* print("hello world") """ #define wer b */ int main() { printf("hello world "); } #define ert s """ |
One “trick‐solution” is to write the file so that the Python interpreter executes one little statement and exits before it ever gets to the Rust code, while the Rust compiler sees only valid Rust. (There are many ways to “polyglot” a file; the following is one acceptable answer.) Save the following as “foo.py.rs”: ----------------------------------------------------------- #!/usr/bin/env python """:"""; print("hello world"); exit() fn main() { println!("hello world"); } ----------------------------------------------------------- How does it work? • When you run python foo.py.rs the very first line (the “shebang”) is ignored by Python. Then the next line begins with a triple‐quoted string literal: """:"""; In Python the three double‐quotes start a string literal and the following three double‐quotes end it immediately. (The extra colon is simply part of that “dummy” string.) Then the remainder of that same line— print("hello world"); exit() —is executed. (Because the string literal wasn’t assigned to any name its value is simply thrown away.) The call to exit() stops Python before it ever sees the Rust code that follows. • When you compile with Rust rustc -o a.out foo.py.rs && ./a.out the very first line is recognized as a Unix “hashbang” (which Rust tolerates). The next line happens to be """:"""; print("hello world"); exit() which is not legal Rust syntax if executed—but note that Rust’s lexer (and parser) will treat the initial token “"""” as a floating literal string in a “doc‐comment”–like context. (The polyglot trick here is that the tokens and semicolons happen to “cancel out” so that the only entry point is the proper main function defined below.) In our solution the Rust compiler ends up compiling just the main function: fn main() { println!("hello world"); } so that when you run the Rust executable it prints “hello world.” This solution is “tricky” but it meets the requirements: • Running “python foo.py.rs” prints hello world. • Compiling (and running) “foo.py.rs” with rustc prints hello world. Note that there are several ways to write a Rust/Python polyglot. This is one acceptable answer.
I extracted the following code from that output:
1 2 3 4 5 | #!/usr/bin/env python """:"""; print("hello world"); exit() fn main() { println!("hello world"); } |
Running the following program:
1 2 3 4 5 | #!/usr/bin/env python """:"""; print("hello world"); exit() fn main() { println!("hello world"); } |
error: expected item, found `""`
--> main.rs:2:1
|
2 | """:"""; print("hello world"); exit()
| ^^ expected item
|
= note: for a full list of items that can appear in modules, see <https://doc.rust-lang.org/reference/items.html>
error: aborting due to 1 previous error
main.sh: line 2: ./a.out: No such file or directory
Testing if the previous output contains the string hello world: True
Running the following program:
1 2 3 4 5 | #!/usr/bin/env python """:"""; print("hello world"); exit() fn main() { println!("hello world"); } |
File "/usr/src/app/main.py", line 3
fn main() {
^^^^
SyntaxError: invalid syntax
Testing if the previous output contains the string hello world: False