I've been experimenting with the mod OpenComputers Drivers for Tinkers Construct lately.
In the absence of coding examples, it's taken me a couple of hours to thrash through the basics, relearn Lua again, up to the point where I can write code that is not utterly ridiculous - and I wanted to share with you peeps. So with no further ado, here's an example for reading the fluids in your smeltery:
local component = require("component")
local smeltery = component.smeltery
local fluids = {smeltery.getContainedFluids()}
for _, fluid in ipairs(fluids) do
print(fluid.label)
end