how to define subclass in *.d.tl

[cloudfreexiao]

some code like this how to define the Lemon type ?

local Fruit = record
end

-- Lemon is Fruit subclassing 
local Lemon = record
end

[pdesaulniers]

Currently, there is no mechanism for this. However, this PR implements tagged records, which may be used to create subtypes:

local Fruit = record
   tag fruit_type: string
end

local Lemon = record is Fruit with fruit_type = "lemon"
end

[hishamhm]

Let's close this as a duplicate of #97, to avoid having the same topic spread across various issues. @cloudfreexiao See you there!