[fine] Design notes, more garbage

fine/design.md

@@ -39,3 +39,28 @@ The `new` keyword is a compromise: we know that the context
 immediately following the `new` keyword is always a type expression,
 so we know that e.g. `<` or whatever means "generic type parameter"
 and not "less than".
+
+## Lambdas/Closures/Anonymous Functions
+
+Looking for a syntax here; I want to keep `fun` as a declaration like
+`let` and not let it enter the expression space. I don't like
+fat-arrow syntax because it makes expression parsing very ambiguous,
+potentially requiring a lot of lookahead. (TODO: Is that true?)
+
+Maybe a leading character like ` \x => x+1 ` or ` \(x,y) => x+y `?
+
+## Interfaces/Traits/Whatever
+
+These are incomplete structural types. Methods are easier to make
+compatible than members, but members should also work so long as they
+are strict prefixes of the thing.
+
+What about sound casting with narrowing? That's union types baby, do
+we really want those? It could be neat if we're doing otherwise
+structural-compatibility.
+
+## On Objects and Classes
+
+Sometimes I think it should all be structural types.
+
+Maybe later there can be anonymous types that match shapes.