feat: improve default morphs, simplify attribute types (#1142)

ark/attest/package.json

@@ -1,6 +1,6 @@
 {
 	"name": "@ark/attest",
-	"version": "0.18.4",
+	"version": "0.19.0",
 	"author": {
 		"name": "David Blass",
 		"email": "david@arktype.io",

ark/fs/package.json

@@ -1,6 +1,6 @@
 {
 	"name": "@ark/fs",
-	"version": "0.13.0",
+	"version": "0.14.0",
 	"author": {
 		"name": "David Blass",
 		"email": "david@arktype.io",

ark/schema/index.ts

@@ -33,6 +33,7 @@ export * from "./shared/implement.ts"
 export * from "./shared/intersections.ts"
 export * from "./shared/jsonSchema.ts"
 export * from "./shared/registry.ts"
+export * from "./shared/traversal.ts"
 export * from "./shared/utils.ts"
 export * from "./structure/index.ts"
 export * from "./structure/optional.ts"

ark/schema/node.ts

@@ -61,14 +61,15 @@ export abstract class BaseNode<
 	/** uses -ignore rather than -expect-error because this is not an error in .d.ts
 	 * @ts-ignore allow instantiation assignment to the base type */
 	out d extends BaseNodeDeclaration = BaseNodeDeclaration
-> extends Callable<(data: d["prerequisite"]) => unknown, attachmentsOf<d>> {
+> extends Callable<
+	(data: d["prerequisite"], ctx?: TraversalContext) => unknown,
+	attachmentsOf<d>
+> {
 	attachments: UnknownAttachments
 	$: BaseScope
 
 	constructor(attachments: UnknownAttachments, $: BaseScope) {
 		super(
-			// pipedFromCtx allows us internally to reuse TraversalContext
-			// through pipes and keep track of piped paths. It is not exposed
 			(data: any, pipedFromCtx?: TraversalContext) => {
 				if (
 					!this.includesMorph &&
@@ -223,19 +224,22 @@ export abstract class BaseNode<
 
 	// Should be refactored to use transform
 	// https://github.com/arktypeio/arktype/issues/1020
-	getIo(kind: "in" | "out"): BaseNode {
+	getIo(ioKind: "in" | "out"): BaseNode {
 		if (!this.includesMorph) return this as never
 
 		const ioInner: Record<any, unknown> = {}
 		for (const [k, v] of this.innerEntries) {
 			const keySchemaImplementation = this.impl.keys[k]
 
-			if (keySchemaImplementation.child) {
+			if (keySchemaImplementation.reduceIo)
+				keySchemaImplementation.reduceIo(ioKind, ioInner, v)
+			else if (keySchemaImplementation.child) {
 				const childValue = v as listable<BaseNode>
+
 				ioInner[k] =
 					isArray(childValue) ?
-						childValue.map(child => child[kind])
-					:	childValue[kind]
+						childValue.map(child => child[ioKind])
+					:	childValue[ioKind]
 			} else ioInner[k] = v
 		}
 

ark/schema/package.json

@@ -1,6 +1,6 @@
 {
 	"name": "@ark/schema",
-	"version": "0.13.0",
+	"version": "0.14.0",
 	"license": "MIT",
 	"author": {
 		"name": "David Blass",

ark/schema/roots/root.ts

@@ -9,7 +9,12 @@ import {
 	type array
 } from "@ark/util"
 import { throwInvalidOperandError, type Constraint } from "../constraint.ts"
-import type { NodeSchema, nodeOfKind, reducibleKindOf } from "../kinds.ts"
+import type {
+	NodeSchema,
+	mutableNormalizedRootOfKind,
+	nodeOfKind,
+	reducibleKindOf
+} from "../kinds.ts"
 import {
 	BaseNode,
 	appendUniqueFlatRefs,
@@ -100,6 +105,11 @@ export abstract class BaseRoot<
 		return this
 	}
 
+	brand(name: string): this {
+		if (name === "") return throwParseError(emptyBrandNameMessage)
+		return this
+	}
+
 	readonly(): this {
 		return this
 	}
@@ -389,7 +399,15 @@ export abstract class BaseRoot<
 						in: branch,
 						morphs: [morph]
 					}),
-			this.$.parseSchema
+			branches => {
+				if (!this.hasKind("union")) return this.$.parseSchema(branches[0])
+				const schema: mutableNormalizedRootOfKind<"union"> = {
+					branches
+				}
+				if ("default" in this.meta) schema.meta = { default: this.meta.default }
+				else if (this.meta.optional) schema.meta = { optional: true }
+				return this.$.parseSchema(schema)
+			}
 		)
 	}
 
@@ -573,6 +591,10 @@ export type UndeclaredKeyConfig = {
 	deep?: boolean
 }
 
+export const emptyBrandNameMessage = `Expected a non-empty brand name after #`
+
+export type emptyBrandNameMessage = typeof emptyBrandNameMessage
+
 export const exclusivizeRangeSchema = <schema extends UnknownRangeSchema>(
 	schema: schema
 ): schema =>

ark/schema/shared/implement.ts

@@ -32,7 +32,7 @@ import type {
 	BaseNormalizedSchema
 } from "./declare.ts"
 import type { Disjoint } from "./disjoint.ts"
-import { isNode } from "./utils.ts"
+import { isNode, type makeRootAndArrayPropertiesMutable } from "./utils.ts"
 
 export const basisKinds = ["unit", "proto", "domain"] as const
 
@@ -277,6 +277,11 @@ export type NodeKeyImplementation<
 		preserveUndefined?: true
 		child?: boolean
 		serialize?: (schema: instantiated) => JsonData
+		reduceIo?: (
+			ioKind: "in" | "out",
+			inner: makeRootAndArrayPropertiesMutable<d["inner"]>,
+			value: d["inner"][k]
+		) => void
 		parse?: (
 			schema: Exclude<d["normalizedSchema"][k], undefined>,
 			ctx: NodeParseContext<d["kind"]>

ark/schema/shared/intersections.ts

@@ -1,10 +1,11 @@
 import type { PartialRecord, TypeGuard } from "@ark/util"
-import type { nodeOfKind } from "../kinds.ts"
+import type { mutableNormalizedRootOfKind, nodeOfKind } from "../kinds.ts"
 import type { BaseNode } from "../node.ts"
 import type { Morph } from "../roots/morph.ts"
 import type { BaseRoot } from "../roots/root.ts"
 import type { Union } from "../roots/union.ts"
 import type { BaseScope } from "../scope.ts"
+import type { BaseMeta } from "./declare.ts"
 import { Disjoint } from "./disjoint.ts"
 import {
 	rootKinds,
@@ -130,9 +131,39 @@ const pipeMorphed = (
 			const viableBranches = results.filter(
 				isNode as TypeGuard<unknown, Morph.Node>
 			)
-			return viableBranches.length === 0 ?
-					Disjoint.init("union", from.branches, to.branches)
-				:	ctx.$.parseSchema(viableBranches)
+
+			if (viableBranches.length === 0)
+				return Disjoint.init("union", from.branches, to.branches)
+
+			if (
+				viableBranches.length < from.branches.length ||
+				!from.branches.every((branch, i) =>
+					branch.in.equals(viableBranches[i].in)
+				)
+			)
+				return ctx.$.parseSchema(viableBranches)
+
+			let meta: BaseMeta | undefined
+
+			if ("default" in from.meta) meta = { default: from.meta.default }
+			else if (from.meta.optional) meta = { optional: true }
+
+			if (viableBranches.length === 1) {
+				const onlyBranch = viableBranches[0]
+				if (!meta) return onlyBranch
+				return ctx.$.node("morph", {
+					...onlyBranch.inner,
+					in: onlyBranch.in.withMeta(meta)
+				})
+			}
+
+			const schema: mutableNormalizedRootOfKind<"union"> = {
+				branches: viableBranches
+			}
+
+			if (meta) schema.meta = meta
+
+			return ctx.$.parseSchema(schema)
 		}
 	)
 
@@ -154,7 +185,7 @@ const _pipeMorphed = (
 
 		return ctx.$.node("morph", {
 			morphs,
-			in: fromIsMorph ? from.in : from
+			in: from.in
 		})
 	}
 

ark/schema/structure/optional.ts

@@ -1,11 +1,20 @@
-import { hasDomain, printable, throwParseError, unset } from "@ark/util"
+import {
+	hasDomain,
+	omit,
+	printable,
+	throwParseError,
+	unset,
+	type keySetOf
+} from "@ark/util"
+import type { Morph } from "../roots/morph.ts"
 import type { BaseRoot } from "../roots/root.ts"
-import type { declareNode } from "../shared/declare.ts"
+import type { BaseMeta, declareNode } from "../shared/declare.ts"
 import { ArkErrors } from "../shared/errors.ts"
 import {
 	implementNode,
 	type nodeImplementationOf
 } from "../shared/implement.ts"
+import { registeredReference } from "../shared/registry.ts"
 import { BaseProp, intersectProps, type Prop } from "./prop.ts"
 
 export declare namespace Optional {
@@ -70,31 +79,80 @@ export class OptionalNode extends BaseProp<"optional"> {
 		}
 	}
 
-	expression = `${this.compiledKey}?: ${this.value.expression}${"default" in this.inner ? ` = ${printable(this.inner.default)}` : ""}`
-}
+	get outProp(): Prop.Node {
+		if (!this.hasDefault()) return this
+		const { default: defaultValue, ...requiredInner } = this.inner
+
+		requiredInner.value = requiredInner.value.withMeta(meta =>
+			omit(meta, optionalValueMetaKeys)
+		)
+
+		return this.cacheGetter(
+			"outProp",
+			this.$.node("required", requiredInner, { prereduced: true }) as never
+		)
+	}
+
+	expression: string = `${this.compiledKey}?: ${this.value.expression}${this.hasDefault() ? ` = ${printable(this.inner.default)}` : ""}`
+
+	defaultValueMorphs: Morph[] = this.computeDefaultValueMorphs()
+
+	defaultValueMorphsReference = registeredReference(this.defaultValueMorphs)
 
-// if (parsedValue.meta) {
-// 	if ("default" in parsedValue.meta) {
-// 		return ctx.$.node("optional", {
-// 			key: parsedKey.key,
-// 			value: parsedValue,
-// 			default: parsedValue.meta.default
-// 		})
-// 	}
-
-// 	if (parsedValue.meta.optional) {
-// 		return ctx.$.node("optional", {
-// 			key: parsedKey.key,
-// 			value: parsedValue
-// 		})
-// 	}
-// }
+	private computeDefaultValueMorphs(): Morph[] {
+		if (!this.hasDefault()) return []
+
+		const defaultInput = this.default
+
+		if (typeof defaultInput === "function") {
+			return [
+				// if the value has a morph, pipe context through it
+				this.value.includesMorph ?
+					(data, ctx) => {
+						ctx.path.push(this.key)
+						this.value((data[this.key] = defaultInput()), ctx)
+						ctx.path.pop()
+						return data
+					}
+				:	data => {
+						data[this.key] = defaultInput()
+						return data
+					}
+			]
+		}
+
+		// non-functional defaults can be safely cached as long as the morph is
+		// guaranteed to be pure and the output is primitive
+		const precomputedMorphedDefault =
+			this.value.includesMorph ? this.value.assert(defaultInput) : defaultInput
+
+		return [
+			hasDomain(precomputedMorphedDefault, "object") ?
+				// the type signature only allows this if the value was morphed
+				(data, ctx) => {
+					ctx.path.push(this.key)
+					this.value((data[this.key] = defaultInput), ctx)
+					ctx.path.pop()
+					return data
+				}
+			:	data => {
+					data[this.key] = precomputedMorphedDefault
+					return data
+				}
+		]
+	}
+}
 
 export const Optional = {
 	implementation,
 	Node: OptionalNode
 }
 
+const optionalValueMetaKeys: keySetOf<BaseMeta> = {
+	default: 1,
+	optional: 1
+}
+
 export const assertDefaultValueAssignability = (
 	node: BaseRoot,
 	value: unknown,