Rust: Types & Traits

Make the wrong program unwriteable

Most Rust is not about the borrow checker. It is about choosing the enum that cannot hold the bad value, carrying a failure as a value instead of throwing it, and naming the one ability a function actually needs — then reading code somebody else wrote and knowing what it does.

Start this project See the modules

Modules: 6
Drills: 10
Build steps: 5
Time: ~4h

Walk out able to

Read unfamiliar Rust and say what it produces — and choose between a generic parameter and a `dyn` without guessing which one the design needs.

What you work on

Enums that refuse bad states

Variants that differ, and a match that has to be total.

Option, Result and ?

Absence and failure carried as values, never thrown.

Generics and traits

One bound per ability — then generic or dyn, on purpose.

Pipelines, then the build

Adapters instead of loops, and a Rust program that runs.

What you get

Skills that stick

Every project mixes short lessons, focused drills and real build steps, so you finish with working code and the judgement behind it.

You will practise

Enum shape, match arms, exhaustiveness
Option, Result, combinators and ?
Trait bounds, dyn, object safety
Iterator chains and the three iters

Afterwards you can

Pick the enum that refuses the bad value
Carry a failure out with ? and no panic
Name the bound a rejected line asked for
Choose a generic or a dyn, and say why

Modules

Step by step

Each module builds on the last. Read a short lesson, drill it until it's second nature, then put it to work.

1
Make the states explicit
~40 min
Choose the type that refuses the bad value, then read any match over it.
- LessonGive the states one type17 min
- DrillChoose the definition that refuses it12 min
- DrillSay which arm runs11 min
2
Absence and failure are values
~39 min
Carry a missing or failed result through a program without unwrapping it.
- LessonCarry the failure instead of throwing it16 min
- DrillSay what the chain evaluates to12 min
- DrillFollow a failure out of a function11 min
3
One function, many types
~25 min
Write a generic function, bound it, and read the error when the bound is missing.
- LessonWrite it once, for every type13 min
- DrillName the bound the body needs12 min
4
Behaviour as a contract
~40 min
Name a behaviour, require it, and choose how the caller carries it.
- LessonName the behaviour, then require it16 min
- DrillPick the one the design needs13 min
- DrillSay whether it can be a trait object11 min
5
Pipelines instead of loops
~36 min
Predict what an adapter chain produces, and start it with the right one of three.
- LessonSay what you want, not how to loop14 min
- DrillSay what the pipeline produces13 min
- DrillStart the loop with the right one9 min
6
Build the reader
~50 min
Get the spellings under your fingers, then ship a Rust program that uses all five.
- DrillWrite the syntax from memory9 min
- Build stepModel the log as one enum5 min
- Build stepFill the type from the text7 min
- Build stepBreak it with one bad number4 min
- Build stepPut the checks behind one trait13 min
- Build stepFinish it with one pipeline12 min