small victory: i managed to implement a love2d dialogue textbox system in fennel using only coroutines

this is the *entire* code to use this

render-text literally is just a coroutine closure that gets resumed every tick, and automatically handles how to render it based on the current time

this is what the closure actually looks like if you're curious! https://gist.github.com/Archenoth/d189ce7b20ea922be3d3169f6b369fef

(i named it .clj because github doesn't recognize fennel)

basically, every tick, the coroutine to render a single line of dialogue resumes with a new time in scope, and based on that, renders a subset of text

after it renders a full line, it continues to a new yield loop to render the bouncy triangle at the bottom to note you can progress

and when the coroutine finally finishes, a new line takes its place

the magic is that resuming a coroutine just jumps right back to the place i yielded from, so i can break this coroutine into tiny pieces that get rendered every frame

meaning, i only ever need to interact with it in once place after making it; it's completely self-contained!

(i wonder how this compares to how scheme continuations work?)

@thingywott

coroutines function almost as a limmitted version of call/cc, gur limit is that they can only be resumed once for each yield

coroutines can actually be implemented with call/cc, something like

(def (m-coroutine yield-fn)
(show-dialog "* farts *")
(call/cc yield-fn)
(show-dialog "pardon me.")
(call/cc yield-fn))

(def co-resume (call/cc m-coroutine)
; * farts * is shown
(set! (call/cc co-resume))
; pardon me. is shown

@thingywott A lil bit of explaination, gur coroutine takes a function to call when its time to yield, gur yield function takes a funciton to call when its time to resume,

call/cc calls a function passing that function another function(ill call this gur "escape function") that can be called to return to gur point of call/cc 's execution (this function can be called an unlimitted number of times)
gur value passed to gur escape function is gur return value for call/cc

@thingywott gur reason we call gur co-routine with call/cc is so that we can come back to where we are when it yields, `yield-fn` is gur escape function supplied by using call/cc,
gur reason for yielding with call/cc is so gur co-routine returns it's own resume funciton

that might not be gur best explaination but i hope it helps!
(i had to implement call/cc myself to actually understand it)

@bx it does, thank you~ ^^

i've known about the existence of generators, coroutines, and continuations for a pretty long time, but i just never used them, so i didn't really internalize the differences between the three

so, when i finally had a reason to actually try out coroutines in fennel, it really seemed like something i could apply a lot more generally--but it also seemed similar to what i remembered thinking when looking at call/cc, hence my curiosity