07 · Pattern Matching
Name a reusable pattern
Declare pattern ActiveUser(name) = User { name, active: true, .. } and reuse it in matching or function clauses. Parameters supply the caller's bindings; constructors resolve where the alias was defined. Alias bodies currently cannot contain view transformers or capture outer values through pins or default expressions.
On this page
Declare pattern ActiveUser(name) = User { name, active: true, .. } and reuse it in matching or function clauses. Parameters supply the caller's bindings; constructors resolve where the alias was defined. Alias bodies currently cannot contain view transformers or capture outer values through pins or default expressions.
Complete example
Name a reusable pattern.
66-pattern-aliases.zolo
// Reuse one selection rule in display logic and filtered iteration.
struct User { name: str, active: bool }
pattern ActiveUser(name) = User { name, active: true, .. }
fn label(value ActiveUser(name): User) -> str = "Active: {name}"
fn label(value _: User) -> str = "Inactive"
let users = [
User { name: "Ana", active: true },
User { name: "Beto", active: false },
]
for case ActiveUser(name) in users { print(name) }
print(label(users[0]))
print(label(users[1]))
Reference
zolo run examples/features/66-pattern-aliases.zolo --no-cache
See also