discretio

Declares a tagged union with variant payloads.

Aliases: union, sum type

Syntax: discretio <name> [<type-params>] <block>

Category

type

Related

• ordo
• discerne
• finge

Examples

examples/corpus/discretio/discretio.fab (canonical · keyword)

Declares a tagged union with variant payloads.

# discretio — tagged union declarations
#
# discretio Nomen {
#     Varians { <type> <field>, ... }
#     Alius
# }
#
# GRAMMAR:
#   discretioDecl :← 'discretio' ident '{' variantDecl* '}'
#   variant     :← ident ('{' fieldDecl (',' fieldDecl)* '}')?
#
# EXPECTED OUTPUT:
#   discretiones paratae

# Discretio with payload variants
discretio Exitus {
    Bonum { textus nuntius }
    Malum { textus causa }
}

# Discretio with mixed unit and payload variants
discretio Actum {
    Pulsus { numerus x, numerus y }
    Clavis { textus clavis }
    # unit variant (no payload fields)
    Finis
}

# Discretio with many fields per variant
discretio Figura {
    Rectum { numerus x, numerus y, numerus latitudo, numerus altitudo }
    Circulus { numerus cx, numerus cy, numerus radius }
    Punctum { numerus x, numerus y }
}

incipit {
    nota "discretiones paratae"
}

Expected output:

discretiones paratae