On: JavaScript Pattern Matching Proposal

[masklinn]

C's switch/case is essentially a special case with a limited set of values (literals) and no destructuring. You can extend it to less trivial patterns and blam pattern matching.

[edflsafoiewq → masklinn]

No, switch is not like a special case of match. C's switch is a kind of computed goto and can build irreducible control flow graphs. match is a reducible structured control-flow construct whose power comes from destructuring. match is much, much more like an if-else chain than a switch.

[masklinn → edflsafoiewq]

> No, switch is not like a special case of match.

Sure is. Or a degenerate one if you prefer.

> match is a reducible structured control-flow construct whose power comes from destructuring.

Match on sum types with no associated data and you have a switch.

> match is much, much more like an if-else chain than a switch.

Depends on what you're matching.

[edflsafoiewq → masklinn]

No it isn't. Again, switch can build irreducible control flow, match cannot. This code

    switch (x) {
    case 0:
        while (i < l) {
            s *= i;
    case 1:
            i += 1;
        }
    }

cannot be rewritten with a simple match. You'd have to reloop the CFG.