Open discussion: Upcoming rewrite of Quantity values in Arturo

[RickBarretto]

This Thread is originates from Discord being written by @drkameleon.

I made just some adaptations to make it easier to read here without change the content.

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The current situation:

• right now, Quantity value literals are basically a number followed by a colon (:) and a unit, e.g. 3:m or 2:m2 (2 square meters)
• I don't particularly like the choice of :... since it normally refers to a value type and not a quantity type/unit
• also, I want the syntax to be able to support far more complicated things, as literal quantities (+ units)... at least, as far as the plan goes, things like 3 kg*m/s2 (at least conceptually) will be totally feasible and the present syntax would over-complicate things
• conversions from-to different units is done using in, like in 'm 3:yd (returns 2.7432:m), but this - using literals as units - wouldn't work with more complicated syntax patterns (see: above^)

So, what I'm thinking:

• Make units a distinct type (preferably with its own literal syntax)
• Make quantities literals like the implicit combination of a number and a unit value
• Since we don't have lots of symbols left (that are also quite light on the eyes and don't create too much clutter), borrow the backtick from char literals (which are current defined as a) for this new type: e.g. myUnit: `m -> (this will be a unit type) and 3`m (this is a quantity).
• Make character literals work as in pretty much every other language (with single quotes), e.g. 'a'

The whole change I'm proposing at a glance:

Before

charA: `a`      ; this is a char
charB: `b`      ; this is a char

3:m + 2:yd      ; adding different quantities together

in 'm2 2:yd2    ; converting quantities to a different unit

After

charA: 'a'      ; this is a char
charB: 'b'      ; this is a char

3`m + 2`yd      ; adding different quantities together

in `m2 2`yd2    ; converting quantities to a different unit

I hope I'm not confusing you too much... 🙂

What do you think?