typus

Declares a type alias.

Aliases: type

Syntax: typus <name> = <type>

Category#

type

Related#

• genus
• implendum
• objectum
• ∪

Examples#

radix/corpus/typus/typus.fab (canonical · keyword)#

Declares a type alias.

# =============================================================================
# typus — Declares a type alias.
# =============================================================================
#
# What this teaches:
#   • Type aliases — `typus` for creating shorthand names for complex types
#   • Generic aliases — aliases can wrap generic types like `lista<T>` and `tabula<K,V>`
#
# Common mistakes:
#   • confusing typus (type alias) with genus (nominal type) — typus creates a transparent alias, not a new type
#
# See also: genus, implendum, objectum, ∪
# =============================================================================




# Type aliases
#
# typus Nomen = Typus
#
# GRAMMAR:
#   typeAliasDecl :← 'typus' ident '=' typeExpr
#
# EXPECTED OUTPUT:
#   42, "Marcus", verum, ["Gaius", "Lucius", "Titus"], [100, 95, 87]

# --- Primitive type aliases ---

type Signum = int
type Cognomen = string
type Viget = bool

# --- Generic type aliases ---

type Nomina = list<string>
type Puncta = list<int>
type Index = map<string, int>

# Nullable type alias (canonical T ∪ nihil form)
type NomenOptivum = string ∪ null

main {
    # Using primitive aliases
    const Signum signum ← 42
    const Cognomen cognomen ← "Marcus"
    const Viget viget ← true

    print signum
    print cognomen
    print viget

    # Using generic aliases
    const Nomina sodales ← ["Gaius", "Lucius", "Titus"]
    print sodales

    const Puncta puncta ← [100, 95, 87]
    print puncta
}