Larry Wall: Com­put­er Pro­gram­ming in 5 Min­utes

• Re­port rights in­fringe­ment
• pub­lished: 13 Jun 2011
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http://​bigthink.​com Com­put­er pro­gram­ming is a lot like writ­ing a recipe. If you've read a recipe, you know what the struc­ture of a recipe is and you can copy the for­mat to cre­ate your own. But then you can take it a lot fur­ther. Ques­tion: Can you ex­plain the ba­sics of the com­put­er pro­gram­ming in five min­utes? Larry Wall:  Well, I can cer­tain­ly try.  Com­put­er pro­gram­ming is re­al­ly a lot like writ­ing a recipe.  If you've read a recipe, you know what the struc­ture of a recipe is, it's got some things up at the top that are your in­gre­di­ents, and below that, the di­rec­tions for how to deal with those in­gre­di­ents. Well, a very sim­i­lar thing hap­pens in a com­put­er pro­gram.  You have, you list out the var­i­ous things that you're going to be deal­ing with, typ­i­cal­ly, and then you have some in­struc­tions that say what to do with those in­gre­di­ents.  So, if you can un­der­stand a recipe and fol­low it in, you know, in your kitchen, then you can pro­gram on that level.  But you can take it a lot far­ther than that.  Many of you, I'm sure, have seen the Iron Chef show, I love to watch that, es­pe­cial­ly if they are given strange in­gre­di­ents. I'm not sure I would like trout ice cream ei­ther, but one of the things that hap­pens there, if you fol­low along, is that the Iron Chef, or who­ev­er the chef is, doesn't ac­tu­al­ly do all the work.  They have what are called sous chefs, that they farm out, sub­di­vide the jobs to, and they'll do the kind of busy work.  And pro­gram­ming is kind of like that, too. You are the head chef, but there are bits and pieces of the com­put­er out there that will do things for you.  Now, it's not quite like Iron Chef, be­cause Iron Chef, you have some fair­ly in­tel­li­gent sous chefs who know how to cod­dle an egg or chop up a fish.  But your com­put­er tends to be more like a bunch of re­al­ly ef­fi­cient robots, but they're very stupid robots and very lit­er­al mind­ed.  So you have to, at some level, you know, tell them ex­act­ly what to do.  But once you've told them, that you can just point to the robot and it'll do the same thing over and over and over again, and do it ex­act­ly the same.  And com­put­ers are like that, that's how they are valu­able, they sort of take over all the bor­ing bits of our think­ing. And then you can kind of take it be­yond that, in­stead of just think­ing of your­self as the chef that's in con­trol, some­times you want to pro­gram more like you're think­ing about how the food ac­tu­al­ly goes through the pro­cess. And maybe even take it up a notch and say, here's a fac­to­ry that pro­duces some food item—Twinkies, or what­ev­er—and you have raw in­gre­di­ents com­ing in—that's as­sum­ing you think Twinkies are food—you have raw in­gre­di­ents com­ing in, and they go on var­i­ous con­vey­or belts and get chopped up in var­i­ous ways and get re­com­bined and there's this flow of the ma­te­ri­als through the fac­to­ry. And even­tu­al­ly it comes back out with some sort of a prod­uct that we con­sid­ered to be food. So there's pro­gram­ming lan­guages that work like that, too, that just talk about how the data runs around in the pro­gram.  For in­stance, your Excel spread­sheet: you're putting data into lit­tle cells, and you have other cells that say, "Well, just make a lit­tle con­vey­or belt of these cells and add them up in this cell."  You're re­al­ly doing pro­gram­ming, even if you think you're just writ­ing cell macros.  So that's like a lit­tle fac­to­ry on your desk­top there. Now going be­yond that, there's var­i­ous ways that you can get into, you know, sort of more high­fa­lutin con­cepts that you would learn if you were tak­ing a com­put­er sci­ence de­gree.  The whole idea of pro­gram­ming on this level is you're say­ing one thing, some ab­stract thing, and that con­trols a bunch of other things.  So the next step that hap­pens is that in­stead of just think­ing about data as the pieces of things you're work­ing with—strings, text, your phone num­bers, what­ev­er. You start think­ing about those bits of recipe, and those recipes can also be con­sid­ered data and can be sent around on the con­vey­or belt in your fac­to­ry.  So it's like a lit­tle con­vey­or that you might have in your café, you put lit­tle things up there that order things up. So when you start talk­ing about ac­tions and ab­stract­ing them, then you can start talk­ing about doing the mul­ti­ple times and loop­ing and this ac­tion may do this ac­tion, which may do that ac­tion, which might come back and do the thing, and you get a re­cur­sive, sort of frac­tal pat­tern.  And so these are the basis of the more math­e­mat­i­cal views of pro­gram­ming, but you don't have to do all that at the be­gin­ning.  You can just start off with the sim­ple recipe idea and add things on as you go and learn as you go.  And then you'll do fine.