diff --git a/docs/dev/README.md b/docs/dev/README.md index 64d595b684..5a9c0a148a 100644 --- a/docs/dev/README.md +++ b/docs/dev/README.md @@ -241,6 +241,26 @@ struct Foo { For `.md` and `.adoc` files, prefer a sentence-per-line format, don't wrap lines. If the line is too long, you want to split the sentence in two :-) +## Preconditions + +Function preconditions should generally be expressed in types and provided by the caller (rather than checked by callee): + +```rust +// Good +fn frbonicate(walrus: Walrus) { + ... +} + +// Not as good +fn frobnicate(walrus: Option) { + let walrus = match walrus { + Some(it) => it, + None => return, + }; + ... +} +``` + # Architecture Invariants This section tries to document high-level design constraints, which are not