Generic's type is always assumed to be a table even when it isn't

[Frityet]

local record Box<T> where (function(k: any): boolean return k is T end)(self.children[1])
    children: {any}
end

local a: Box<integer> | Box<string> = (function(): Box<integer> return { children = { 1 } } end)()

if not a is Box<integer> then error "pluh" end

errors with pluh, even though it should be valid, this is because the code generates to

local a = (function() return { children = { 1, "two", "thrwee" } } end)(); if not (function(k) return type(k) == "table"





end)(a.children[1]) then error("pluh") end

whilst it should be math.type(k) == "integer"

[Nikita-baghela07]

The problem is that generics in Teal default to being treated as table at runtime, so Box is incorrectly checked with type(k) == "table" instead of math.type(k) == "integer".

so u need an explicit type guard for primitives,
e.g. wrap the check in a helper function:

local function isIntegerBox(b) return math.type(b.children[1]) == "integer" end if not isIntegerBox(a) then error("pluh")

[Frityet]

The problem is that generics in Teal default to being treated as table at runtime, so Box is incorrectly checked with type(k) == "table" instead of math.type(k) == "integer".

so u need an explicit type guard for primitives, e.g. wrap the check in a helper function:

local function isIntegerBox(b) return math.type(b.children[1]) == "integer" end if not isIntegerBox(a) then error("pluh")

Generics in teal aren't treated as anything at runtime, theres no reason why the codegen can't be specialised