Vararg check?

[freddylist]

t doesn't have a way to check varargs (if there is, then it's not documented and should be documented / I couldn't find it). You could, of course, t.array(check)({...}) inside the function to check, but you can't do that with t.wrap.

I suggest passing the last remaining arguments in a t.tuple check to the last check:

function t.tuple(...)
	local checks = { ... }
	local checkCount = #checks -- or `select('#', ...)`, whichever is fastest ig idk

	return function(...)
		local args = { ... }

		for i, check in ipairs(checks) do
			-- Pass any remaining arguments to the last check:
			local success, errMsg
			
			if i == checkCount then
				success, errMsg = check(select(i, ...))
			else
				success, errMsg = check(args[i])
			end

			if success == false then
				return false, string.format("Bad tuple index #%s:\n\t%s", i, errMsg or "")
			end
		end

		return true
	end
end

And adding a vararg check:

function t.vararg(check)
	assert(t.callback(check))

	return function(...)
		for i, v in ipairs({...}) do
			local success, errMsg = check(v)

			if success == false then
				return false, string.format("Bad vararg index #%s:\n\t%s", i, errMsg or "")
			end
		end
		
		return true
	end
end

This way, I can check varargs in wrapped functions! :D

local add = t.wrap(function(a, b, ...)
	local total = a + b
	
	for _, v in pairs({...}) do
		total += v
	end
	
	return total
end, t.tuple(t.number, t.number, t.vararg(t.number)))

print(add(1, 2, 3, 4, 5)) -- 15
print(add(1, 2, 3, 4, "a") -- error: bad tuple index 3, bad vararg index 3

I didn't open a pull request because I don't want to mess up those typescript thingies. The code here could probably be improved as well, but if you want, I can open a pull request with tests and I will do my best to do the typescript stuff correctly.