Language philosophy

The design rules

1. Small grammar

Every keyword must remove more complexity than it adds. The grammar is kept small on purpose. A feature that only saves a little typing but adds a new thing to learn does not get in.

2. Methods on values

Primitive values have methods too: 5.abs() works without boxing the integer. Structs copy by value, while classes have reference semantics. Beans also supports standalone functions and closures.

3. No null, no exceptions

There is no null and there are no exceptions anywhere in the language. A value that might be missing has type Option<T>. An operation that might fail returns Result<T>. Callers handle both through ordinary values.

4. Every new name states its type

There is no type inference on let, var, function parameters, fields, or loop variables. You write the type. Code stays readable without an editor to tell you what things are.

There is one exception: match bindings. In a match, the value being matched already pins the type, so the binding does not repeat it.

match find_user(id) {
    some(u) => io.println(u.name),  // u's type comes from the match
    none    => io.println("not found"),
}

5. One casing rule

• snake_case for functions, methods, variables, packages, and enum variants.
• PascalCase for types.
• lowercase for primitives (int, bool, decimal, string).

The casing tells you what a name is before you read anything else.

6. Package-private by default

Classes, interfaces, enums, functions, methods, and fields stay inside their package unless you mark them pub, so you do not leak API by accident. A field or method that must stay inside its own declaring type uses priv; same-package code and subclasses still cannot access it.

7. If two designs work, pick the one with less syntax

When two designs both do the job, Beans takes the one that reads with fewer symbols. That tie-breaker is behind many small choices.

Why Option is capitalized but some is not

The casing rule (rule 5) does all the work here:

• PascalCase means a type. Option<User> is a type.
• snake_case means a value. some(u) is a value.

Option and Result are not special syntax. They are built-in enums, and enum variants are snake_case, so the variants are some, none, ok, and err, all lowercase.

let found: Option<User> = some(user)   // Option = type, some = value
let missing: Option<User> = none

For how to use them day to day, see Option and Result. The goals and non-goals page lists what Beans deliberately leaves out.