type fixes and bindings + notes on subtyping

docs/about/interpret.md

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+# interpretation of sappho
+
+Different aspects of sappho interpreted.
+
+## What is true?
+
+Our "set interpretation" of types says `true` represents the full universe of
+"things".
+
+What are these things?
+
+For all intents and purposes, a programmer can look at them as the values of
+our language.
+
+What does this mean in practical terms?
+
+Well, it means something of type `true` is "a value".
+
+What is "a value" then?
+
+That's a good question. It can be anything really.
+
+An integer?
+
+Yep!
+
+A function?
+
+Yes, m'am!
+
+A solution to the halting problem?
+
+Well, yeah! But good luck constructing that.
+
+A...
+
+I think you get my point. A value can be anything from a simple integer to
+nuclear apocalypse. The thing is, from the point of view of our program, it
+means "we cannot really say anything here".
+
+But couldn't that be dangerous?
+
+Depends on what you mean by dangerous.
+
+I mean, to be able to give everything a type?
+
+Well, let me ask you this: do you like rat poison?
+
+What? To eat?
+
+Yeah!
+
+Nooo, that'd be dangerous!
+
+Yeah, exactly my point.
+
+What?
+
+You know what rat poison is obviously, despite it being dangerous?
+
+Well, yeah...
+
+Maybe you got it already, but my point is: rat poison is dangerous, but you
+still know about it, and its existance. So, something being dangerous does not
+mean you have this blank spot of knowledge that you just keep ignoring because
+of this perceived danger.
+
+
+
+
+
+### interpretation of ⊢
+what is the interpretation of
+
+γ ⊢ δ?
+
+
+given a concrete type k
+
+conjunction of γ hold for k
+
+then 
+
+disjunction of δ hold for k
+
+
+
+