- cross-posted to:
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- cross-posted to:
- [email protected]
- [email protected]
Made with KolourPaint and screenshots from Kate (with the GitHub theme).
Made with KolourPaint and screenshots from Kate (with the GitHub theme).
Go’s syntax is vastly superior once you have more complicated signatures, then the left-to-right truly matters. For example a variable that contains a pointer to a function that takes a function and an int and returns another function (like a decorator).
In C the order becomes very hard to understand and you really have to read the thing several times to understand the type of fp:
int (*(*fp)(int (*)(int, int), int))(int, int)In Go, you can just read from left to right and you can easily understand what f’s type is:
f func(func(int,int) int, int) func(int, int) intIt’s just much more readable.
See: https://go.dev/blog/declaration-syntax
If you actually use code like this you’re insane.
This obviously just illustrates a point, but callbacks and decorators are not uncommon. And iterators are exactly like that:
type ( Seq[V any] func(yield func(V) bool) Seq2[K, V any] func(yield func(K, V) bool) )Which is very readable.
Callbacks and decorators are fine, but callbacks/decorators to a function which itself takes a function pointer and returns another function pointer are crazy.
I’ve thankfully never had to use recursive callbacks or decorators, but it seems like it could very quickly become difficult to keep track of.
I don’t think it’s that uncommon. Let’s say you have a function that handles a request. A common use case is to add permission checks before applying that function. You can write a generic permission check a bit like this:
func NeedsPermission(f func(Request) (Response, error), perm string) func(Request) (Response, error) { return func(r Request) (Response, error) { if !check(r, perm) { return nil, NewPermError(perm) } return f(r) } } // elsewhere Bar := NeedsPermission(Foo, "superman")This would allow you to separate the permission check logic from the business logic. Though to be fair, in Go they prefer to keep things as simple as possible but it’s just to illustrate that these concepts are not that alien.
Wait until you learn about transducers (Are they in Go? If not natively, someone definitely ported them) and the abominations fp people code with them.
To be fair, the C example could be detangled a lot by introducing a typedef:
typedef int Callback_t(int, int);Callback_t *(*fp)(Callback_t *, int);True, but that requires writing an additional definition and hides the parameter types, which can be very interesting, and you’d need a typedef for every new param combination I guess. It feels like a solution for a problem that could have been avoided by a better signature syntax in the first place.