enlist.r3

Rebol [
    name:     enlist
    purpose: "Format series to human readable list"
    usage: [
        print enlist []      ;= none
        print enlist [1]     ;= just 1
        print enlist [1 2]   ;= 1 and 2
        print enlist [1 2 3] ;= 1, 2 and 3
    ]
    note: https://gitter.im/red/help?at=5f9c02f906fa0513dd8119d1
]

enlist: function [
	"Format series to human readable list"
	block [block!]
][
	ajoin switch/default len: length? block [
		0 [[none]]
		1 [["just " block/1]]
	][
		i: 1 out: clear ""
		loop len - 2 [ append append out block/(++ i) ", " ]
		[out block/:i " and " block/:len]
	]
]