Order, Fork and Trek

Order went first, because Order almost always goes first. Order's whole nature is the right things in the right order — step one, then step two, then step three; never step two before step one, never the ending before the middle. Order lays the path down one careful stone at a time, and the program walks it exactly as laid. "People think I'm fussy," Order said, setting a stone. "But watch what happens if I'm not." Order swapped two stones — just two, just for a second — and the whole path buckled and threw the program flat on its face. "See? Pour the cereal, then the milk. Wake up, then stand. Open the box, then look inside. Same steps, wrong order — and nothing works. That's sequence. I'm not fussy. I'm the one who remembers that when is part of what." Order set the two stones back where they belonged, and the path lay smooth again.

But then the path reached a place where it split, and this was Fork's whole reason for being. Fork stood at the split and did the one thing Order never could: Fork chose. Not ahead of time, not by guessing — Fork looked at what was true right now, this very second, and picked the branch that fit. "Is the door open?" Fork asked the air. The air said yes. "Then we go left." And left they went. A moment later the path split again. "Is it raining?" No. "Then we go right, no umbrella." Fork never fretted over the branch not taken; a choice wasn't a worry, just a clear look at a condition and a steady step onto the branch that matched. "Order knows the steps," said Fork, "but the world keeps changing under our feet. Somebody has to look up and decide which way this time, based on what's true. That's selection. That's me."

And then the path did a curious thing: it curled around and came back to where it had started, and Trek's face lit up, because a loop was Trek's favourite place in all the realm. Trek ran it. Then ran it again. And again — because Trek's whole nature is keep going around until the work is done, not once, not twice, but as many times as it takes. Fold one shirt, come back, fold the next; water one plant, come back, water the next; take one step of a hundred, come back, take the next. "Doesn't it get boring?" Order asked. "That's the trick," said Trek, rounding the bend. "You don't write a hundred steps. You write one — and I run it a hundred times. One instruction, and I'll go around till every shirt's folded and every plant's watered and there's nothing left on the list. That's iteration." Trek slowed as the last of the work came up empty. "And I stop when it's done — that's the part people forget to love about me. I don't go forever. I go until the condition says the job's finished, and then I rest." (A loop that never checks its stopping condition is the one bug that does go forever.)