Clutch goes to floor after trans reinstall

Just put the trans back together from a rebuild, changed the clutch while it was all apart. Complete clutch kit.
If I push in the clutch, it just drops to the floor. I can see the cylinder has pushed all the way out and the lever is maxed. It just stays there like that.
Now, I can reach down and use my hand to push the lever back, and this pushes the cylinder back in (and subsequently the clutch pedal pops back up, but the lever going into the trans mostly just hangs out there so now there is floppiness between the end of the clutch cylinder and the lever.
What's up w/ this? Basically it feels like there is very little really pushing the lever back down, e.g. trying to compress the clutch cylinder back.

I have not bled the clutch, but I don't see how that would matter.

If you compressed the slave at all, you'll need to pump it a few times, like you need to do with a brake caliper that's been compressed. Push the pedal to the floor and pull it back up with your hand.

Also, if you took the lines apart, you'll need to bleed it.

^this.

Allright, thanks.
I did not open the lines any, but yes I did of course have to compress the cylinder to get it off of the housing. So I'll try manually pumping a few times before I get too worried, and plan to bleed it for good measure anyway.
.
However the more I think about it, I just don't see what is pushing the clutch back up?

Clutch pedal or what releases the clutch from the pressure plate?