I don't really agree with their argument, though. Pretty much all the features that Babel deals with are syntax sugar, in the sense that if they didn't exist, you could largely emulate them at runtime by writing a bit more code or using a library. The sugar adds a layer of abstraction, but it's a very thin layer, enough that most JavaScript developers could compile (or transpile) the sugar away in their head.
On the other hand, C to Assembly is not such a thin layer of abstraction. Even the parts that seem relatively simple can change massively as soon as an optimisation pass is involved. There is a very clear difference in abstraction layer going on here.
I'll give you that these definitions are fuzzy. Nim uses a source-to-source compiler, and the difference in abstraction between Nim and C certainly feels a lot smaller than the difference between C and Assembly. But the C that Nim generates is, as I understand it, very low-level, and behaves a lot closer to assembly, so maybe in practice the difference in abstraction is greater than it initially seems? I don't think there's a lot of value in trying to make a hard-and-fast set of rules here.
However, it's clear that there is a certain subset of compilers that aim to do source-to-source desugaring transformations, and that this subset of compilers have certain similarities and requirements that mean it makes sense to group them together in some way. And to do that, we have the term "transpiler".
On the other hand, C to Assembly is not such a thin layer of abstraction. Even the parts that seem relatively simple can change massively as soon as an optimisation pass is involved. There is a very clear difference in abstraction layer going on here.
I'll give you that these definitions are fuzzy. Nim uses a source-to-source compiler, and the difference in abstraction between Nim and C certainly feels a lot smaller than the difference between C and Assembly. But the C that Nim generates is, as I understand it, very low-level, and behaves a lot closer to assembly, so maybe in practice the difference in abstraction is greater than it initially seems? I don't think there's a lot of value in trying to make a hard-and-fast set of rules here.
However, it's clear that there is a certain subset of compilers that aim to do source-to-source desugaring transformations, and that this subset of compilers have certain similarities and requirements that mean it makes sense to group them together in some way. And to do that, we have the term "transpiler".