[bjacks]

Can anyone explain what a sequential programming language is?

Context here:

"I guess I’d underestimated the difficulty of implementing Anything-over-TCP in a sequential language. Just because it’s really really easy in Erlang doesn’t mean to say it’s easy in sequential languages."

[perishabledave]

I think he's referring to how Erlang uses the Actor Model. An Erlang program consists of (possibly) thousands of individual lightweight-processes. In this model a typical task may be spread out over many asynchronous processes. You can think of it as a program thats made up of thousands of micro-services. Instead of a task taking place over a sequential piece of code, it takes places over many individual processes that coordinate by communicating with each other.

[Gracana]

Imperative programming. Lists of statements, vs Erlang's declarative programming, where you describe the program without specifying control flow.

[white-flame]

Erlang is absolutely a fixed in-order control flow programming language, on message receipt. It is (generally) referentially transparent, but not declarative.

[Gracana]

Oh, I don't know much about Erlang so I thought for sure that's what he meant. What was that supposed to mean, then?

[xrstf]

Given that he is contrasting to Erlang, maybe he's talking about imperative languages instead of (pure) functional ones?

[dwc]

Erlang's pattern matching allows a great many things to be done in a declarative style. For some problems you end up with a lot of pattern stuff and not all that much "normal" code. Or you pattern match through what would ordinarily be a lot of flow control statements, for each case writing very simple code to handle that one thing.

Since Erlang isn't a declarative language in the larger sense, that's my guess what he meant.