Match.tag on union of unions
I have something like that:
When I have unions that have _tag that can be unions or derived from unions, the
I know I can use
type E1 = 'A' | 'B' | 'C'
type E2 = 'D' | 'E' | 'F'
type E3 = 'G' | 'H' | 'I'
type Example = {
_tag: E1,
where: 'A~C'
aNumber?: never
} | {
_tag: E2,
where: 'D~F'
aNumber: number
} | {
_tag: E3,
where: 'G~I'
aString: string
}
declare const example: Example
Match.value(example).pipe(
Match.tag('A', () => 1),
Match.tag('B', () => 2),
Match.tag('C', () => 3),
Match.tag('D', () => 4),
Match.tag('E', () => 5),
Match.tag('F', () => 6),
Match.tag('G', () => 7),
Match.tag('H', () => 8),
Match.tag('I', (x) => 9), // x: never
Match.exhaustive // error
)
Match.value(example).pipe(
Match.when({_tag: 'A'}, () => 1),
Match.when({_tag: 'B'}, () => 2),
Match.when({_tag: 'C'}, () => 3),
Match.when({_tag: 'D'}, () => 4),
Match.when({_tag: 'E'}, () => 5),
Match.when({_tag: 'F'}, () => 6),
Match.when({_tag: 'G'}, () => 7),
Match.when({_tag: 'H'}, () => 8),
Match.when({_tag: 'I'}, (x) => 9), // (parameter) x: {
// _tag: "I";
// where: "G~I";
// aString: string;
// }
Match.exhaustive // works as expected
)type E1 = 'A' | 'B' | 'C'
type E2 = 'D' | 'E' | 'F'
type E3 = 'G' | 'H' | 'I'
type Example = {
_tag: E1,
where: 'A~C'
aNumber?: never
} | {
_tag: E2,
where: 'D~F'
aNumber: number
} | {
_tag: E3,
where: 'G~I'
aString: string
}
declare const example: Example
Match.value(example).pipe(
Match.tag('A', () => 1),
Match.tag('B', () => 2),
Match.tag('C', () => 3),
Match.tag('D', () => 4),
Match.tag('E', () => 5),
Match.tag('F', () => 6),
Match.tag('G', () => 7),
Match.tag('H', () => 8),
Match.tag('I', (x) => 9), // x: never
Match.exhaustive // error
)
Match.value(example).pipe(
Match.when({_tag: 'A'}, () => 1),
Match.when({_tag: 'B'}, () => 2),
Match.when({_tag: 'C'}, () => 3),
Match.when({_tag: 'D'}, () => 4),
Match.when({_tag: 'E'}, () => 5),
Match.when({_tag: 'F'}, () => 6),
Match.when({_tag: 'G'}, () => 7),
Match.when({_tag: 'H'}, () => 8),
Match.when({_tag: 'I'}, (x) => 9), // (parameter) x: {
// _tag: "I";
// where: "G~I";
// aString: string;
// }
Match.exhaustive // works as expected
)When I have unions that have _tag that can be unions or derived from unions, the
Match.tagMatch.tag behave differently from Match.whenMatch.when maybe it's an uncommon use-case but I was wondering why and if it's something that could be consistent.I know I can use
Match.whenMatch.when with Match.isMatch.is in combo, but the Match.tagMatch.tag is so much better 
