The convert: boolean approach

src/boxes.ts

@@ -46,7 +46,7 @@ function skipFree(tree: Tree): Tree {
 
 function words(tree: Tree): string {
 	if ('word' in tree) {
-		if (tree.word === 'covert') {
+		if (tree.word.covert) {
 			return '';
 		} else {
 			return tree.word.text;
@@ -91,7 +91,7 @@ function boxifyClause(tree: Tree): BoxClause {
 	if (!('left' in cp)) throw new Error('bad CP?');
 	const c = cp.left;
 	if (!('word' in c)) throw new Error('C without word?');
-	if (c.word !== 'covert') {
+	if (!c.word.covert) {
 		complementizer = c.word.text;
 	}
 	for (let node = cp.right; ; ) {
@@ -149,7 +149,7 @@ export function boxify(tree: Tree): BoxSentence {
 	const sa = tree.right;
 	if (sa.label !== 'SA') throw new Error('SAP without SA?');
 	if (!('word' in sa)) throw new Error('SA without word?');
-	if (sa.word !== 'covert') {
+	if (!sa.word.covert) {
 		speechAct = sa.word.text;
 	}
 	const cp = tree.left;

src/compact.ts

@@ -1,7 +1,7 @@
 import { Branch, Leaf, Tree, nodeType } from './tree';
 
 function isCovert(tree: Tree): boolean {
-	return 'word' in tree && typeof tree.word === 'string';
+	return 'word' in tree && tree.word.covert;
 }
 
 export function compact(tree: Tree): Tree {

src/draw-tree.ts

@@ -50,10 +50,9 @@ export function placeLeaf(
 	ctx: CanvasRenderingContext2D,
 	leaf: Leaf | (Leaf & { denotation: Expr | null }),
 ): PlacedLeaf {
-	const gloss =
-		typeof leaf.word === 'string' ? undefined : leaf.word.entry?.gloss;
+	const gloss = leaf.word.covert ? undefined : leaf.word.entry?.gloss;
 	const label = getLabel(leaf);
-	const word = leaf.word === 'covert' ? leaf.value : leaf.word.text;
+	const word = leaf.word.covert ? leaf.word.value : leaf.word.text;
 	const denotation =
 		'denotation' in leaf && leaf.denotation !== null
 			? toPlainText(leaf.denotation)

src/english.ts

@@ -13,7 +13,7 @@ function leafText(tree: Tree): string {
 	if (!('word' in tree)) {
 		throw new Error('Unexpected non-leaf ' + tree.label);
 	}
-	if (tree.word === 'covert') return '';
+	if (tree.word.covert) return '';
 	return tree.word.text;
 }
 
@@ -47,7 +47,7 @@ function verbToEnglish(tree: Tree): string {
 }
 
 function serialToEnglish(serial: Tree): string {
-	if ('word' in serial && serial.word === 'covert') return '';
+	if ('word' in serial && serial.word.covert) return '';
 	if (serial.label !== '*Serial') throw new Error('non-*Serial serial');
 	if (!('children' in serial)) throw new Error('non-Rose serial');
 	return serial.children.map(x => verbToEnglish(x)).join('-');
@@ -363,7 +363,7 @@ function branchToEnglish(tree: Branch<Tree>): Constituent {
 			{ she: 'necessarily', ao: 'would', daı: 'possibly', ea: 'could' }[
 				bare(leafText(modal))
 			] ?? '?';
-		if (c.word === 'covert') {
+		if (c.word.covert) {
 			return { text: eng };
 		} else {
 			return {

src/latex.ts

@@ -26,7 +26,7 @@ export function toLatex(tree: Tree | DTree): string {
 		const children = tree.children.map(toLatex).join(' ');
 		return `[${label} ${children}]`;
 	} else {
-		if (tree.word === 'covert') {
+		if (tree.word.covert) {
 			return `[${label} [$\\varnothing$]]`;
 		}
 

src/semantics/denote.ts

@@ -410,14 +410,14 @@ function denoteLeaf(leaf: Leaf, cCommand: StrictTree | null): DTree {
 	let bindings = noBindings;
 
 	if (leaf.label === 'V') {
-		if (typeof leaf.word === 'string') throw new Error();
+		if (leaf.word.covert) throw new Error('covert V');
 		const entry = leaf.word.entry;
 		if (!entry) throw new Error();
 		if (entry.type !== 'predicate') throw new Error();
 
 		denotation = denoteVerb(entry.toaq, entry.frame.split(' ').length);
 	} else if (leaf.label === 'DP') {
-		if (leaf.word === 'covert') {
+		if (leaf.word.covert) {
 			denotation = hoa;
 			bindings = covertHoaBindings;
 		} else if (leaf.word.entry === undefined) {
@@ -518,8 +518,8 @@ function denoteLeaf(leaf: Leaf, cCommand: StrictTree | null): DTree {
 		};
 	} else if (leaf.label === '𝘷') {
 		let toaq: string | null;
-		if (leaf.word === 'covert') {
-			toaq = leaf.value;
+		if (leaf.word.covert) {
+			toaq = leaf.word.value;
 		} else if (leaf.word.entry === undefined) {
 			throw new Error(`Unrecognized 𝘷: ${leaf.word.text}`);
 		} else {
@@ -528,7 +528,7 @@ function denoteLeaf(leaf: Leaf, cCommand: StrictTree | null): DTree {
 		denotation = denoteLittleV(toaq);
 	} else if (leaf.label === 'Asp') {
 		let toaq: string;
-		if (leaf.word === 'covert') {
+		if (leaf.word.covert) {
 			toaq = 'tam';
 		} else if (leaf.word.entry === undefined) {
 			throw new Error(`Unrecognized Asp: ${leaf.word.text}`);
@@ -538,7 +538,7 @@ function denoteLeaf(leaf: Leaf, cCommand: StrictTree | null): DTree {
 
 		denotation = denoteAspect(toaq);
 	} else if (leaf.label === 'T') {
-		if (leaf.word === 'covert') {
+		if (leaf.word.covert) {
 			denotation = defaultTense;
 		} else if (leaf.word.entry === undefined) {
 			throw new Error(`Unrecognized T: ${leaf.word.text}`);
@@ -549,7 +549,7 @@ function denoteLeaf(leaf: Leaf, cCommand: StrictTree | null): DTree {
 		denotation = null;
 	} else if (leaf.label === 'SA') {
 		let toaq: string;
-		if (leaf.word === 'covert') {
+		if (leaf.word.covert) {
 			toaq = 'da'; // TODO: covert móq
 		} else if (leaf.word.entry === undefined) {
 			throw new Error(`Unrecognized SA: ${leaf.word.text}`);

src/serial.ts

@@ -2,11 +2,11 @@ import { Branch, Label, Tree } from './tree';
 
 const arityPreservingVerbPrefixes: Label[] = ['buP', 'muP', 'buqP', 'geP'];
 
-const pro: Tree = { label: 'DP', word: 'covert', value: 'PRO' };
+const pro: Tree = { label: 'DP', word: { covert: true, value: 'PRO' } };
 
 export function getFrame(verb: Tree): string {
 	if ('word' in verb) {
-		if (verb.word === 'covert') throw new Error('covert verb?');
+		if (verb.word.covert) throw new Error('covert verb?');
 		if (verb.word.entry?.type === 'predicate') {
 			return verb.word.entry.frame;
 		} else {
@@ -41,7 +41,7 @@ function serialTovP(verbs: Tree[], args: Tree[]): Tree {
 		if (arity === 1) {
 			return {
 				label: '𝘷P',
-				left: { label: '𝘷', word: 'covert', value: 'BE' },
+				left: { label: '𝘷', word: { covert: true, value: 'BE' } },
 				right: { label: 'VP', left: verbs[0], right: args[0] },
 			};
 		} else if (arity === 2) {
@@ -50,7 +50,7 @@ function serialTovP(verbs: Tree[], args: Tree[]): Tree {
 				left: args[0],
 				right: {
 					label: "𝘷'",
-					left: { label: '𝘷', word: 'covert', value: 'CAUSE' },
+					left: { label: '𝘷', word: { covert: true, value: 'CAUSE' } },
 					right: { label: 'VP', left: verbs[0], right: args[1] },
 				},
 			};
@@ -60,7 +60,7 @@ function serialTovP(verbs: Tree[], args: Tree[]): Tree {
 				left: args[0],
 				right: {
 					label: "𝘷'",
-					left: { label: '𝘷', word: 'covert', value: 'CAUSE' },
+					left: { label: '𝘷', word: { covert: true, value: 'CAUSE' } },
 					right: {
 						label: 'VP',
 						left: args[1],
@@ -94,7 +94,7 @@ function serialTovP(verbs: Tree[], args: Tree[]): Tree {
 		if (arity === 1) {
 			return {
 				label: '𝘷P',
-				left: { label: '𝘷', word: 'covert', value: 'BE' },
+				left: { label: '𝘷', word: { covert: true, value: 'BE' } },
 				right: { label: 'VP', left: verbs[0], right: inner },
 			};
 		} else if (arity === 2) {
@@ -103,7 +103,7 @@ function serialTovP(verbs: Tree[], args: Tree[]): Tree {
 				left: args[0],
 				right: {
 					label: "𝘷'",
-					left: { label: '𝘷', word: 'covert', value: 'CAUSE' },
+					left: { label: '𝘷', word: { covert: true, value: 'CAUSE' } },
 					right: { label: 'VP', left: verbs[0], right: inner },
 				},
 			};
@@ -113,7 +113,7 @@ function serialTovP(verbs: Tree[], args: Tree[]): Tree {
 				left: args[0],
 				right: {
 					label: "𝘷'",
-					left: { label: '𝘷', word: 'covert', value: 'CAUSE' },
+					left: { label: '𝘷', word: { covert: true, value: 'CAUSE' } },
 					right: {
 						label: 'VP',
 						left: args[1],
@@ -135,20 +135,19 @@ function attachAdjective(VP: Tree, vP: Tree): Tree {
 			label: 'aP',
 			left: {
 				label: 'a',
-				word: 'covert', // TODO ki
-				value: '∅',
+				word: { covert: true, value: '∅' }, // TODO ki
 			},
 			right: {
 				// TODO: oh god, adjectives can have T and Asp?
 				// needs rework in nearley grammar
 				label: 'CPrel',
-				left: { label: 'C', word: 'covert', value: '∅' },
+				left: { label: 'C', word: { covert: true, value: '∅' } },
 				right: {
 					label: 'TP',
-					left: { label: 'T', word: 'covert', value: '∅' },
+					left: { label: 'T', word: { covert: true, value: '∅' } },
 					right: {
 						label: 'AspP',
-						left: { label: 'Asp', word: 'covert', value: '∅' },
+						left: { label: 'Asp', word: { covert: true, value: '∅' } },
 						right: vP,
 					},
 				},

src/textual-tree.ts

@@ -2,8 +2,7 @@ import { Tree } from './tree';
 
 function ttree_converted(data: Tree): { label: string; branches: any } {
 	if ('word' in data) {
-		const b =
-			data.word === 'covert' ? data.value : data.word.text.toLowerCase();
+		const b = data.word.covert ? data.word.value : data.word.text.toLowerCase();
 		return { label: data.label, branches: [b] };
 	} else if ('left' in data) {
 		return {

src/tree.ts

@@ -4,13 +4,21 @@ import { bare, clean, ToaqToken, tone } from './tokenize';
 import { Tone } from './types';
 
 export interface Word {
+	covert: false;
 	index: number | undefined;
 	text: string;
 	bare: string;
 	tone: Tone;
 	entry: Entry | undefined;
 }
 
+type CovertValue = '∅' | 'BE' | 'CAUSE' | 'PRO';
+
+export interface CovertWord {
+	covert: true;
+	value: CovertValue;
+}
+
 export type Label =
 	| '*Serial'
 	| '*𝘷P'
@@ -86,7 +94,7 @@ export function containsWords(
 	stopLabels: Label[],
 ): boolean {
 	if ('word' in tree) {
-		return tree.word !== 'covert' && words.includes(clean(tree.word.text));
+		return !tree.word.covert && words.includes(clean(tree.word.text));
 	} else if ('left' in tree) {
 		return (
 			(!stopLabels.includes(tree.left.label) &&
@@ -111,25 +119,13 @@ export function isQuestion(tree: Tree): boolean {
 	);
 }
 
-export interface OvertLeaf {
+export interface Leaf {
 	label: Label;
 	id?: string;
 	movedTo?: string;
-	word: Word;
+	word: Word | CovertWord;
 }
 
-type CovertValue = '∅' | 'BE' | 'CAUSE' | 'PRO';
-
-export interface CovertLeaf {
-	label: Label;
-	id?: string;
-	movedTo?: string;
-	word: 'covert';
-	value: CovertValue;
-}
-
-export type Leaf = OvertLeaf | CovertLeaf;
-
 export interface Branch<T> {
 	label: Label;
 	left: T;
@@ -154,6 +150,7 @@ export function makeWord([token]: [ToaqToken]): Word {
 	const lemmaForm = token.value.toLowerCase().normalize();
 	const bareWord = bare(token.value);
 	return {
+		covert: false,
 		index: token.index,
 		text: token.value,
 		bare: bareWord,
@@ -182,7 +179,7 @@ export function makeLeaf(label: Label) {
 export function makeCovertLeaf(label: Label) {
 	return () => ({
 		label,
-		word: 'covert',
+		word: { covert: true, value: '∅' },
 	});
 }
 
@@ -200,7 +197,7 @@ export function makeBranchCovertLeft(label: Label, covertLabel: Label) {
 	return ([right]: [Tree, Tree]) => {
 		return {
 			label,
-			left: { label: covertLabel, word: 'covert' },
+			left: { label: covertLabel, word: { covert: true, value: '∅' } },
 			right,
 		};
 	};
@@ -245,7 +242,7 @@ export function makeSingleChild(label: Label) {
 
 export function makeOptLeaf(label: Label) {
 	return ([leaf]: [Leaf | undefined]) => {
-		return leaf ?? { label, word: 'covert' };
+		return leaf ?? { label, word: { covert: true, value: '∅' } };
 	};
 }
 
@@ -302,7 +299,7 @@ export function makevPdet([serial]: [Tree], location: number, reject: Object) {
 	}
 	return {
 		label: '*𝘷P',
-		children: [serial, { label: 'DP', word: 'covert' }],
+		children: [serial, { label: 'DP', word: { covert: true, value: '∅' } }],
 	};
 }
 
@@ -356,14 +353,14 @@ export function makeT1ModalvP([modal, tp]: [Tree, Tree]) {
 			left: modal,
 			right: {
 				label: 'CP',
-				word: 'covert',
+				word: { covert: true, value: '∅' },
 			},
 		},
 		right: {
 			label: "𝘷'",
 			left: {
 				label: '𝘷',
-				word: 'covert',
+				word: { covert: true, value: 'BE' },
 			},
 			right: tp,
 		},
@@ -396,13 +393,17 @@ export function makePrefixP([prefix, verb]: [Tree, Tree]) {
 export function makeRetroactiveCleft([tp, vgo, clause]: [Tree, Tree, Tree]) {
 	return {
 		label: '𝘷P',
-		left: { label: 'CP', left: { label: 'C', word: 'covert' }, right: tp },
+		left: {
+			label: 'CP',
+			left: { label: 'C', word: { covert: true, value: '∅' } },
+			right: tp,
+		},
 		right: {
 			label: "𝘷'",
 			left: vgo,
 			right: {
 				label: 'CPrel',
-				left: { label: 'C', word: 'covert' },
+				left: { label: 'C', word: { covert: true, value: '∅' } },
 				right: clause,
 			},
 		},