So I've read that the slipknot is considered the first stitch of a project.
Is the slipknot a knit or a purl?
If it's a knit, then how does one start with a purl?
I know how to do long-tail casts for knits and for purls, but the first stitch (the slipknot) confuses me in this regard.
It does not matter whether that first stitch is a knit or purl, it will not impact the whole of the project. It will hardly been seen if left open like a shawl, it will be hidden in the seam when you make an item out of several panels.
If you feel is it important, you can make one (or a few) extra cast on stitches and take out that first (or those extra) one(s) leaving all the stitches knit or purl as you like. You can undo the extra cast on stitches easiest if you left them drop from the needle when turning around at the end of the row, and cutting through the loop of the slipknot if they do not fall away naturally.
The way I learned to cast on there was no way to make knit or purl, it was just cast on and it worked. I have later learned a knitting way to cast on and in those you can make a difference but it mostly does not matter.
The slipknot can either be a purl or knit stitch, I looked at it closely and there is a purl bump and a V (a small reminder that knits and purls are the same but reversed). It'd be easy to switch it based on your pattern because you can just take it off flip it and put it back, although it won't make a big difference since it's one stitch among an edge, which is bound to look different than the rest of the work, and it's one stitch of hundreds(for most things).
The bottom line is if you look closely you can tell whether or not it's a purl or knit(it can differ based on your slipknot tying technique) and you can choose which one you want.
