Created
October 31, 2023 20:17
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Decoder
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| import type { ParseOptions } from "@effect/schema/AST" | |
| import * as Parser from "@effect/schema/Parser" | |
| import * as PR from "@effect/schema/ParseResult" | |
| import * as S from "@effect/schema/Schema" | |
| import { pipe } from "effect" | |
| const TypeId: unique symbol = Symbol.for("@typed/decoder/decoder") as TypeId | |
| export type TypeId = typeof TypeId | |
| interface Decoder<I, O> { | |
| [TypeId]: TypeId | |
| decode(i: I, options?: ParseOptions): PR.ParseResult<O> | |
| } | |
| interface SchemaDecoder<From, To = From> extends S.Schema<From, To>, Decoder<unknown, To> {} | |
| function fromSchema<From, To>(schema: S.Schema<From, To>): SchemaDecoder<From, To> { | |
| return { | |
| ...schema, | |
| [TypeId]: TypeId, | |
| decode(i: unknown, options?: ParseOptions): PR.ParseResult<To> { | |
| return Parser.validate(schema)(i, options) | |
| } | |
| } | |
| } | |
| function map<A, B>(f: (a: A) => B): <I>(decoder: Decoder<I, A> | S.Schema<I, A>) => Decoder<I, B> { | |
| return (decoder) => { | |
| const _decoder: Decoder<any, any> = (decoder as any)[TypeId] === TypeId | |
| ? (decoder as Decoder<any, any>) | |
| : fromSchema(decoder as S.Schema<any, any>) | |
| return ({ | |
| [TypeId]: TypeId, | |
| decode: (i: any, options?: ParseOptions) => PR.map(_decoder.decode(i, options), f) | |
| }) | |
| } | |
| } | |
| function parse<A, B>(f: (a: A) => PR.ParseResult<B>): <I>(decoder: Decoder<I, A> | S.Schema<I, A>) => Decoder<I, B> { | |
| return (decoder) => { | |
| const _decoder: Decoder<any, any> = (decoder as any)[TypeId] === TypeId | |
| ? (decoder as Decoder<any, any>) | |
| : fromSchema(decoder as S.Schema<any, any>) | |
| return ({ | |
| [TypeId]: TypeId, | |
| decode: (i: any, options?: ParseOptions) => PR.flatMap(_decoder.decode(i, options), f) | |
| }) | |
| } | |
| } | |
| // TODO: compose | |
| const WordsSplit = S.string.pipe( | |
| parse((a) => | |
| a.indexOf(" ") !== -1 | |
| ? PR.success(a.split(" ") as [string, string, ...Array<string>]) | |
| : PR.failure(PR.type(S.string.ast, a, "must contain at least one word")) | |
| ) | |
| ) | |
| const SecondWord = pipe(WordsSplit, map((a) => a[1])) | |
| const SecondWordSplitByO = pipe( | |
| SecondWord, | |
| parse((a) => | |
| a.indexOf("o") !== -1 | |
| ? PR.success(a.split("o") as [string, string, ...Array<string>]) | |
| : PR.failure(PR.type(S.string.ast, a, "must contain at least one 'o'")) | |
| ) | |
| ) | |
| const SecondWordSplitByOTailLength = pipe(SecondWordSplitByO, map((a) => a[1].length)) | |
| SecondWordSplitByOTailLength.decode("hello world") // ? | |
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