Skip to main content

Choosing an Assignment Operator

If you were to write your own programming language (as I still intend to do someday even if only for the learning experience it provides me), what symbol (or symbols) would you use to represent the assignment operator?

Even though it would looks like BNF or old-school Pascal, I would lean towards using := as the assignment operator. That would leave me free to use = for equality and there wouldn't be the issue of = vs. == tripping up new programmers. Besides, performing assignments is more common than making comparisons, so perhaps assignment should have the more distinct operator. Going one step further, if the language I wrote was not strongly typed, I would use == as the identity operator (as like PHP's ===). := and = to == seems a more logical progression to me than = and == to ===.

I suspect I wouldn't use = as both assignment and comparison as Basic does because of the ambiguity it causes. For example:
x = y = 0
Does this mean "assign 0 to both x and y", or "assign the boolean comparison whether the value of y is 0 to x?" Statements such as these:
x := y = 0
x := y := 0
are then both clear in their meaning.

I think my second choice would be just : and have something like:
x: 2 + 2
The lvalue appears as if it were a label, giving the visual representation that x means 2 + 2. Plus, it would be one (of many) syntaxtic differences that would separate my language from the others. I don't know of any languages that currently use : as an assignment operator.

Of course, this all presumes the elements of a statement are written in a certain order. If you were to use a keyword such as set:
x set 2 + 2
just appears awkward to me. It would have to be:
set x 2 + 2
But if you always require the assignment target on the left-hand side of your operator, then is an explicit assignment operator really required as all? The implied assignment operation of something like:
x 2 + 2
is clean and succinct.

Comments

  1. This makes visual sense to me.

    x <- 2 + 2

    ReplyDelete
  2. I’d like to use “←” for assignment! ;-)
    x ← 2 + 2
    NB my favorite OS doesn't star with “Windows…” but ends with “…Linux” |-D

    ReplyDelete

Post a Comment

Popular posts from this blog

Composing Music with PHP

I’m not an expert on probability theory, artificial intelligence, and machine learning. And even my Music 201 class from years ago has been long forgotten. But if you’ll indulge me for the next 10 minutes, I think you’ll find that even just a little knowledge can yield impressive results if creatively woven together. I’d like to share with you how to teach PHP to compose music. Here’s an example: You’re looking at a melody generated by PHP. It’s not the most memorable, but it’s not unpleasant either. And surprisingly, the code to generate such sequences is rather brief. So what’s going on? The script calculates a probability map of melodic intervals and applies a Markov process to generate a new sequence. In friendlier terms, musical data is analyzed by a script to learn which intervals make up pleasing melodies. It then creates a new composition by selecting pitches based on the possibilities it’s observed. . Standing on Shoulders Composition doesn’t happen in a vacuum. Bach wa

Learning Prolog

I'm not quite sure exactly I was searching for, but somehow I serendipitously stumbled upon the site learnprolognow.org a few months ago. It's the home for an introductory Prolog programming course. Logic programming offers an interesting way to think about your problems; I've been doing so much procedural and object-oriented programming in the past decade that it really took effort to think at a higher level! I found the most interesting features to be definite clause grammars (DCG), and unification. Difference lists are very powerful and Prolog's DCG syntax makes it easy to work with them. Specifying a grammar such as: s(s(NP,VP)) --> np(NP,X,Y,subject), vp(VP,X,Y). np(np(DET,NBAR,PP),X,Y,_) --> det(DET,X), nbar(NBAR,X,Y), pp(PP). np(np(DET,NBAR),X,Y,_) --> det(DET,X), nbar(NBAR,X,Y). np(np(PRO),X,Y,Z) --> pro(PRO,X,Y,Z). vp(vp(V),X,Y) --> v(V,X,Y). vp(vp(V,NP),X,Y) --> v(V,X,Y), np(NP,_,_,object). nbar(nbar(JP),X,3) --> jp(JP,X). pp(pp(PREP,N

What's Wrong with OOP

Proponents of Object Oriented Programming feel the paradigm yields code that is better organized, easier to understand and maintain, and reusable. They view procedural programming code as unwieldy spaghetti and embrace OO-centric design patterns as the "right way" to do things. They argue objects are easier to grasp because they model how we view the world. If the popularity of languages like Java and C# is any indication, they may be right. But after almost 20 years of OOP in the mainstream, there's still a large portion of programmers who resist it. If objects truly model the way people think of things in the real world, then why do people have a hard time understanding and working in OOP? I suspect the problem might be the focus on objects instead of actions. If I may quote from Steve Yegge's Execution in the Kingdom of Nouns : Verbs in Javaland are responsible for all the work, but as they are held in contempt by all, no Verb is ever permitted to wander about