Add comments throughout.

terms/Term.ts

@@ -1,33 +1,42 @@
+/**
+ * Term.ts contains the type information for parsing user sentences.
+ */
+
 import Player from "../Player.ts";
 import Scene from "../Scene.ts";
 
+// ActionFn is the signature for functions that contain the logic associated with verbs
+// the player uses.
 export type ActionFn = (
 	player: Player,
 	scene: Scene,
-	target?: string,
-	object?: string
-) => string;
+	target?: string, // the target is the target of the action.
+	object?: string // the object is an item that is used with the action on the target.
+) => string; // should return a description of the result for the player.
 
+// Constant is a specific word that the engine knows about. If the player uses a word
+// that is not a Constant, then it should be a variable that represents something that
+// is defined in the writer's story files.
 export interface Constant {
 	constant: string;
 	category: Category;
 }
 
-export type Category =
-	| "action"
-	| "direction"
-	| "compound"
-	| "position"
-	| "interaction";
+// Category is a union of the different kinds of Constants.
+export type Category = "action" | "direction" | "position" | "interaction";
 
+// Term describes a known word that the player can use. It tells the parse what kinds of
+// words can come after it and what it means.
 export interface Term {
-	precedesCategories: Category[];
-	precedesConstants: Constant[];
-	category: Category;
-	constant: string;
-	canPrecedeVariable: boolean;
+	precedesCategories: Category[]; // categories of Constant that can follow this Term
+	precedesConstants: Constant[]; // Constants that can follow this Term
+	category: Category; // the category of this Terms Constant is part of
+	constant: string; // the name of the Constant that this Term describes
+	canPrecedeVariable: boolean; // indicates that what follows might be a variable
 }
 
+// ActionTerm extends Term, adding the function needed to execute a verb. It also
+// guarentees that the category is "action".
 export interface ActionTerm extends Term {
 	action: ActionFn;
 	category: "action";