I often get distracted by new things to study. Some are rather old, Erlang, Haskell, and others are fairly new, PureScript, Rust. I am not looking to master these skills, but at least understand how to use them.
I always find mountains of theoretical resources like books and videos. These allow me to hit the floor running, but I rarely remember most of it. I need a more hands-on approach to actually learn things.
I used to build clones of well know services. This was useful to learn architectures and frameworks, but I am passed this now. My new approach is Exercism driven learning.
Exercism is a service that hosts programming exercises and test cases. There are many alternatives, like CodinGame and HackerRank. I picked Exercism, but any other would work.
To get started with Exercism you need to create an account. Next, you should install their command-line tool and configure it. This will allow you to fetch the exercises and submit your solutions. If you prefer, all their exercises are available on GitHub.
Let’s use Exercism and solve their first Rust exercise.
$ exercism fetch rust
Not Submitted: 1 problem
rust (Hello World) /Users/pvinchon/exercism/rust/hello-world
New: 1 problem
rust (Hello World) /Users/pvinchon/exercism/rust/hello-world
unchanged: 0, updated: 0, new: 1
Let’s have a look at what was just downloaded.
$ cd /Users/pvinchon/exercism/rust/hello-world
$ ls -l
total 24
-rw-r--r-- 1 pvinchon staff 49 16 May 23:37 Cargo.toml
-rw-r--r-- 1 pvinchon staff 2166 16 May 23:37 GETTING_STARTED.md
-rw-r--r-- 1 pvinchon staff 2238 16 May 23:37 README.md
drwxr-xr-x 3 pvinchon staff 96 16 May 23:37 src
drwxr-xr-x 3 pvinchon staff 96 16 May 23:37 tests
This problem, like all other Exercism Rust problems, is a Cargo project. It follows clear conventions, allowing you to focus on your solution and not on how to run the tests.
$ cargo test
Compiling hello-world v1.1.0 (file:///Users/pvinchon/exercism/rus...
Finished dev [unoptimized + debuginfo] target(s) in 0.79 secs
Running target/debug/deps/hello_world-4625680145752437
running 0 tests
test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 fil...
Running target/debug/deps/hello_world-a78f9d761c0415c2
running 1 test
test test_hello_world ... FAILED
failures:
---- test_hello_world stdout ----
thread 'test_hello_world' panicked at 'assertion failed: ...
left: `"Hello, World!"`,
right: `"Goodbye, World!"`', tests/hello-world.rs:5:5
note: Run with `RUST_BACKTRACE=1` for a backtrace.
failures:
test_hello_world
test result: FAILED. 0 passed; 1 failed; 0 ignored; 0 measured; 0...
error: test failed, to rerun pass '--test hello-world'
A test is currently failing. The goal is to make sure all tests pass. In this scenario, the solution isn’t hard to find.
// In src/lib.rs
// The &'static here means the return type has a static lifetime.
// This is a Rust feature that you don't need to worry about now.
pub fn hello() -> &'static str {
// Replace "Goodbye" by "Hello"
"Hello, World!"
}
Once src/lib.rs has been updated, we can run the tests again.
$ cargo test
Compiling hello-world v1.1.0 (file:///Users/pvinchon/exercism/rus...
Finished dev [unoptimized + debuginfo] target(s) in 0.0 secs
Running target/debug/deps/hello_world-4625680145752437
running 0 tests
test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 fil...
Running target/debug/deps/hello_world-a78f9d761c0415c2
running 1 test
test test_hello_world ... ok
test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 fil...
Doc-tests hello-world
running 0 tests
test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 fil...
One test has passed and none have failed or been ignored. Tests are ignored if they have the #[ignore] attribute. To run ignored tests, manually remove the attribute, or run cargo test -- --ignored.
To fetch the next exercise, we must first submit our solution.
$ exercism submit src/lib.rs
Your rust solution for hello-world has been submitted.
Programmers generally spend far more time reading code than writing it. To benefit the most from this exercise, find 3 or more submissions that you can learn something from, have questions about, or have suggestions for. Post your thoughts and questions in the comments, and start a discussion. Consider revising your solution to incorporate what you learn.
Yours and others' solutions to this problem:
http://exercism.io/tracks/rust/exercises/hello-world
$ exercism fetch
Not Submitted: 1 problem
rust (Gigasecond) /Users/pvinchon/exercism/rust/gigasecond
New: 1 problem
rust (Gigasecond) /Users/pvinchon/exercism/rust/gigasecond
unchanged: 0, updated: 0, new: 1
There are currently 82 problems for Rust, enough to keep you occupied for days. Other languages are available too if you prefer.
Overall Exercism is a great tool to learn new languages or improve your skills. I hope you will find use for it.