Rules

Errors · How values convert · Names and case · Order of operations · Shared and plain values · True and false · Variables

Errors

When something goes wrong I stop the script and tell you the file, the line, what happened and — when I have one — a tip for what to try next. A function can also hand back an error as a value with ERROR(code, values). That only stops the script if it gets used as an ordinary value, so the caller can test it first with ISERROR.

How values convert

I convert values for you in a few places, and only these.

A whole number and a float together give a float. / always gives a float and \ always gives a whole number.

A string joins with anything using +: I turn the other side into text. A string times a number repeats the string. The one exception is an array on the left: list + "text" adds the string to the array.

When you compare a string with a number, I read the string as a number, so "5" = 5 and "10" > 9 are true. A string that isn’t a number is not equal to any number, and I can’t put it in order against one.

Dividing by a coordinate, or ordering one with < or >, uses the coordinate’s length: with p = (3, 4), 10 / p is 2.0 and p > 4 is true.

The bit operators &, |, ~, << and >> take whole numbers only — not even a float with nothing after the point.

Nothing else converts. "5" - 1 and (1, 2) + 1 stop me with an error — I’d rather ask than guess!

Names and case

I don’t mind how you capitalise keywords, names and fields: Print, PRINT and print are all the same to me. A map key written in quotes keeps its exact case, and you reach it with map("Key").

A name is a letter or _ followed by letters, digits and _. The reserved words are mine, so they can’t be used as names.

Order of operations

Here’s the order I work things out in, tightest first. Operators on the same row go left to right, except ^. When in doubt, add parentheses — I never mind them.

Shared and plain values

Numbers, strings, ranges, coordinates and vectors are plain values: assigning one makes a separate copy. Arrays, maps and objects are shared: assigning one gives you a second name for the same thing.

True and false

To me, NULL, 0, 0.0 and errors are false. Everything else is true — including an empty string, an empty array and an empty map. Comparisons, AND, OR and NOT give the integers 1 and 0.

Variables

Assigning to a name makes a variable the whole program shares — or, inside a NAMESPACE, one that belongs to that namespace. LOCAL makes one that belongs to the function it’s in, and ATOMIC marks a shared one that several threads change at once. If you read a name that nothing ever assigns, I catch it when the script loads — before a single line has run.