Numerics in Radian

Initially, Radian handled numbers as basic integers only.  The way floating-point support was implemented was by using the dot operator as a function which would take two integers (the left-hand side and the right-hand side) and return a floating-point value.  However, this also meant that it was basically impossible for us to write any backend support for special processing of numerics.  Also, it meant that it was possible to write some funky things, like:

var wahoo = 12
var blah = 1.wahoo
if blah = 1.12 then
end if

In theory, that would work fine because the dot operator function would concatenate 1 and wahoo (12) together.

Now Radian has lexical support for more numeric formats than just integers.  The support is highly based off of Python, so those of you coming from that language should feel right at home.  We now support integers, floating-point values, hexadecimal, octal and binary literals.  All of the various literal formats are still considered to be a “number” internally, and there basically is no support for coercion aside from what the backend does via C.  Eventually, we’d like to see a numeric tower like Scheme, where each numeric format builds on top of a lower abstraction.  However, that project will wait for another day.

Currently, the syntax for numeric literals is:

Integers:    [1-9][0-9]* | 0
Floats:        [0-9]+.[0-9]+
Hexadecimal:    0[Xx][0-9A-Fa-f]+
Octal:        0[Oo][0-7]+
Binary:        0[Bb][0-1]+

You’ll notice that there is not support for scientific notation with floats, which will likely change in the future.  Also, I’m not supporting sign information as part of the numeric literal.  When you apply a sign, we treat it as an operator currently.  I’m not too keen on that right now because I think it will make constant folding a bit more difficult.  Also, I’m still on the fence as to whether I want to support a unary + as well as a unary – in the same way that Python (and JavaScript, etc) does.  I can’t think of reasonable use cases that aren’t contrived or too clever.

Hello!

Introductory posts always scare me — I feel like I’m applying for a job.  :-P

My name is Aaron Ballman, and I’m one of the contributors to the Radian project (and blog).  I started working on compilers with Mars while we were both at REAL Software, and eventually worked my way up to being the lead compiler architect on REALbasic once he moved on to greener pastures at Microsoft.  I’m currently employed by 4D, Inc doing compiler-ish type work on several languages, including JavaScript and SQL.

I’ve been involved with Radian in one way or another for a few years now.  However, it’s only recently that my involvement has started to ramp up into actual productivity instead of just acting as a sounding board.  I’m really looking forward to working with Mars on the language design and implementation work for Radian.

Don’t be too shocked if you see blog posts from me in the future.  At least you now know who I am!  ;-)