Comment by throwawaymaths
Comment by throwawaymaths 20 hours ago
> you can’t call a function that takes IO from inside a function that does not is false, since you can initialize one to pass it in
that's not true. suppose a function foo(anytype) takes a struct, and expects method bar() on the struct.
you could send foo() the struct type Sync whose bar() does not use io. or you could send foo() the struct type Async whose bar uses an io stashed in the parameter, and there would be no code changes.
if you don't prefer compile time multireification, you can also use type erasure and accomplish the same thing with a vtable.
It's hard to parse your comment, but I think we are agreeing? I was refuting the point of the parent. you have given another example of calling an IO-taking function inside a non-IO taking function. the example I gave was initializing an IO inside the non-IO taking function. you could also, as pointed out elsewhere, use global state.