Symbols

[liquidev]

One neat feature Ruby has is symbols - unique identifiers, where two different symbols with the same name are equal:

p :yes == :yes  # true

I think Mica should get a similar feature, though much less dynamic. Unlike strings, symbols should not cause allocations. Their use case would be similar to enums in statically typed languages. For instance, a LÖVE-like API might use symbols for specifying if rectangles should be filled or outlined:

Graphics.rectangle(:fill, 32, 32, 32, 32)
Graphics.rectangle(:line, 32, 32, 32, 32)

In NaN-tagged mode, symbols should use the unused values of ValueImpl::SIGN_ENUM NaNs - those past nil, false, and true. The values for symbols should be stored in the environment, such that symbols are comparable across all scripts run by the same engine.