feat: chainable constraints (#995)

Author: ssalbdivad

.changeset/cuddly-dingos-approve.md

@@ -0,0 +1,5 @@
+---
+"@arktype/util": patch
+---
+
+Add `leftIfEqual` type utility

.changeset/tender-wombats-march.md

@@ -0,0 +1,5 @@
+---
+"@arktype/schema": patch
+---
+
+Fixed a cyclic traversal case (see [arktype CHANGELOG](../type/CHANGELOG.md))

ark/dark/package.json

@@ -2,7 +2,7 @@
 	"name": "arkdark",
 	"displayName": "ArkDark",
 	"description": "ArkType syntax highlighting and theme⛵",
-	"version": "5.2.2",
+	"version": "5.2.3",
 	"publisher": "arktypeio",
 	"type": "module",
 	"scripts": {
@@ -59,11 +59,11 @@
 			},
 			"errorLens.replace": [
 				{
-					"matcher": "^(?:Type|Argument of type) '.*' is not assignable to (?:parameter of )?type 'keyError<\"(.*)\">'\\.$",
+					"matcher": "'keyError<\"(.*)\">'\\.$",
 					"message": "$1"
 				},
 				{
-					"matcher": "^(?:Type|Argument of type) '.*' is not assignable to (?:parameter of )?type '\"(.*\\u200A)\"'\\.$",
+					"matcher": "'\"(.*\\u200A)\"'\\.$",
 					"message": "$1"
 				},
 				{

ark/schema/api.ts

@@ -17,6 +17,7 @@ export * from "./predicate.js"
 export * from "./refinements/after.js"
 export * from "./refinements/before.js"
 export * from "./refinements/divisor.js"
+export * from "./refinements/exactLength.js"
 export * from "./refinements/max.js"
 export * from "./refinements/maxLength.js"
 export * from "./refinements/min.js"

ark/schema/ast.ts

@@ -1,7 +1,8 @@
-import type { conform } from "@arktype/util"
+import type { conform, leftIfEqual } from "@arktype/util"
 import type { PrimitiveConstraintKind } from "./constraint.js"
 import type { NodeSchema } from "./kinds.js"
 import type { constraintKindOf } from "./roots/intersection.js"
+import type { MorphAst, Out } from "./roots/morph.js"
 
 export type Comparator = "<" | "<=" | ">" | ">=" | "=="
 
@@ -126,6 +127,11 @@ export type LessThanLength<rule extends number> = {
 	max: { [k in rule]: 0 }
 }
 
+export type ExactlyLength<rule extends number> = {
+	min: { [k in rule]: 1 }
+	max: { [k in rule]: 1 }
+}
+
 export namespace string {
 	export type atLeastLength<rule extends number> = of<
 		string,
@@ -144,6 +150,11 @@ export namespace string {
 		LessThanLength<rule>
 	>
 
+	export type exactlyLength<rule extends number> = of<
+		string,
+		ExactlyLength<rule>
+	>
+
 	export type matching<rule extends string> = of<string, Matching<rule>>
 
 	export type narrowed = of<string, Narrowed>
@@ -164,6 +175,7 @@ export namespace string {
 					lessThanLength<rule & number>
 				:	atMostLength<rule & number>
 			: kind extends "regex" ? matching<rule & string>
+			: kind extends "exactLength" ? exactlyLength<rule & number>
 			: narrowed
 		:	never
 }
@@ -227,11 +239,9 @@ export type constrain<
 	kind extends PrimitiveConstraintKind,
 	schema extends NodeSchema<kind>
 > =
-	_constrain<t, kind, schema> extends infer constrained ?
-		[t, constrained] extends [constrained, t] ?
-			t
-		:	constrained
-	:	never
+	t extends MorphAst<infer i, infer o> ?
+		(In: leftIfEqual<i, _constrain<i, kind, schema>>) => Out<o>
+	:	leftIfEqual<t, _constrain<t, kind, schema>>
 
 type _constrain<
 	t,
@@ -282,6 +292,7 @@ export type schemaToConstraint<
 			schema extends { exclusive: true } ?
 				LessThanLength<rule & number>
 			:	AtMostLength<rule & number>
+		: kind extends "exactLength" ? ExactlyLength<rule & number>
 		: kind extends "after" ?
 			schema extends { exclusive: true } ?
 				After<normalizeLimit<rule>>

ark/schema/constraint.ts

@@ -6,7 +6,7 @@ import {
 	throwInternalError,
 	throwParseError,
 	type array,
-	type describeExpression,
+	type describe,
 	type listable,
 	type satisfy
 } from "@arktype/util"
@@ -247,9 +247,9 @@ export const writeInvalidOperandMessage = <
 export type writeInvalidOperandMessage<
 	kind extends ConstraintKind,
 	actual extends Root
-> = `${Capitalize<kind>} operand must be ${describeExpression<
+> = `${Capitalize<kind>} operand must be ${describe<
 	Prerequisite<kind>
->} (was ${describeExpression<Exclude<actual["infer"], Prerequisite<kind>>>})`
+>} (was ${describe<Exclude<actual["infer"], Prerequisite<kind>>>})`
 
 export interface ConstraintAttachments {
 	impliedBasis: UnknownRoot | null

ark/schema/keywords/internal.ts

@@ -6,7 +6,7 @@ import { arrayIndexMatcher } from "../structure/shared.js"
 import "./tsKeywords.js"
 
 export interface internalKeywordExports {
-	lengthBoundable: string | unknown[]
+	lengthBoundable: string | readonly unknown[]
 	propertyKey: Key
 	nonNegativeIntegerString: string
 }

ark/schema/predicate.ts

@@ -11,14 +11,16 @@ import type {
 	TraverseApply
 } from "./shared/traversal.js"
 
-export interface PredicateInner<rule extends Predicate<any> = Predicate<any>>
+export interface PredicateInner<predicate extends Predicate = Predicate>
 	extends BaseMeta {
-	readonly predicate: rule
+	readonly predicate: predicate
 }
 
 export type PredicateErrorContext = Partial<PredicateInner>
 
-export type PredicateSchema = PredicateInner | Predicate<any>
+export type PredicateSchema<predicate extends Predicate = Predicate> =
+	| PredicateInner<predicate>
+	| predicate
 
 export interface PredicateDeclaration
 	extends declareNode<{
@@ -87,7 +89,7 @@ export class PredicateNode extends BaseConstraint<PredicateDeclaration> {
 	}
 }
 
-export type Predicate<data = unknown> = (
+export type Predicate<data = any> = (
 	data: data,
 	ctx: TraversalContext
 ) => boolean
@@ -97,7 +99,7 @@ export type PredicateCast<input = never, narrowed extends input = input> = (
 	ctx: TraversalContext
 ) => input is narrowed
 
-export type inferNarrow<t, predicate> =
+export type inferPredicate<t, predicate> =
 	predicate extends (data: any, ...args: any[]) => data is infer narrowed ?
 		t extends of<unknown, infer constraints> ?
 			constrain<of<narrowed, constraints>, "predicate", any>

ark/schema/refinements/after.ts

@@ -9,20 +9,20 @@ import {
 	BaseRange,
 	parseDateLimit,
 	parseExclusiveKey,
-	type BaseNormalizedRangeRoot,
 	type BaseRangeInner,
-	type LimitRootValue
+	type LimitSchemaValue,
+	type UnknownNormalizedRangeSchema
 } from "./range.js"
 
 export interface AfterInner extends BaseRangeInner {
 	rule: Date
 }
 
-export interface NormalizedAfterSchema extends BaseNormalizedRangeRoot {
-	rule: LimitRootValue
+export interface NormalizedAfterSchema extends UnknownNormalizedRangeSchema {
+	rule: LimitSchemaValue
 }
 
-export type AfterSchema = NormalizedAfterSchema | LimitRootValue
+export type AfterSchema = NormalizedAfterSchema | LimitSchemaValue
 
 export interface AfterDeclaration
 	extends declareNode<{

ark/schema/refinements/before.ts

@@ -10,20 +10,20 @@ import {
 	BaseRange,
 	parseDateLimit,
 	parseExclusiveKey,
-	type BaseNormalizedRangeRoot,
 	type BaseRangeInner,
-	type LimitRootValue
+	type LimitSchemaValue,
+	type UnknownNormalizedRangeSchema
 } from "./range.js"
 
 export interface BeforeInner extends BaseRangeInner {
 	rule: Date
 }
 
-export interface NormalizedBeforeSchema extends BaseNormalizedRangeRoot {
-	rule: LimitRootValue
+export interface NormalizedBeforeSchema extends UnknownNormalizedRangeSchema {
+	rule: LimitSchemaValue
 }
 
-export type BeforeSchema = NormalizedBeforeSchema | LimitRootValue
+export type BeforeSchema = NormalizedBeforeSchema | LimitSchemaValue
 
 export interface BeforeDeclaration
 	extends declareNode<{