Some sort of POC to improve the way Effect reports errors in a dev env 🤔
Had to re-export runSync and runPromise to apply prettyPrint function on the cause returned by a catchAll.
So using it would look like this :
import { runPromise } from 'effect-errors'; await runPromise( Effect.gen(function* () { // ... }), );
You can also directly import the prettyPrint function to do whatever you want with it 🤷
import { prettyPrint } from 'effect-errors'; await Effect.runPromise( pipe( Effect.gen(function* () { // ... }), Effect.sandbox, Effect.catchAll((e) => { console.error(prettyPrint(e)); return Effect.fail('❌ runPromise failure'); }), ), );
Signature is the following:
const prettyPrint: <E>(cause: Cause<E>, options?: PrettyPrintOptions) => string
PrettyPrintOptions allows you to tweak the following:
default:
true
default:
false(absolute paths)
default:
true
You can also use the function prettyPrintFromCapturedErrors to display errors from captured errors:
import { NodeFileSystem } from '@effect/platform-node'; import { Effect, pipe } from 'effect'; import { TaggedError } from 'effect/Data'; import { captureErrors, prettyPrintFromCapturedErrors } from 'effect-errors'; export class MyCustomError extends TaggedError('MyCustomError')<{ cause?: unknown; message?: string; }> {} const task = pipe( Effect.fail( new MyCustomError({ cause: 'Well this sucks', }), ), Effect.withSpan('task', { attributes: { isCool: true }, }), ); const program = pipe( task, Effect.sandbox, Effect.catchAll((e) => Effect.gen(function* () { const errors = yield* captureErrors(e); const message = prettyPrintFromCapturedErrors(errors, { stripCwd: true, hideStackTrace: true, }); console.error(message); // Do something with the captured errors ... }), ), Effect.provide(NodeFileSystem.layer), Effect.withSpan('program', { attributes: { name: 'cool' } }), ); Effect.runPromise(program);
The result would look like so:
The best way is to use either SchemaError or TaggedError.
Declaring the error could look like this:
import { Schema } from 'effect'; export class FileNotFoundError extends Schema.TaggedError<SchemaError>()( 'FileNotFound', { cause: Schema.Defect, }, ) {}
You would then raise a FileNotFoundError to the error channel like this:
Effect.tryPromise({ try: () => ..., catch: (e) => new FileNotFoundError({ cause: e }), }); // or raising directly Effect.fail(new FileNotFoundError({ cause: "Oh no!" }));
export class UserNotFoundError extends TaggedError('UserNotFound')<{ cause?: unknown; }> {}
You would then raise a UserNotFoundError to the error channel like this:
Effect.tryPromise({ try: () => ..., catch: (e) => new UserNotFoundError({ cause: e }), }); // or raising directly Effect.fail(new UserNotFoundError({ cause: "User does not exist" }));
Alternatively, you can use a plain object with a _tag and message attribute, but you won't get any stacktrace if you use this method:
Effect.fail({ _tag: 'SucksToBeMe', message: 'Yeah...' });
You might want to apply your own logic to reported errors data; for example if you want to display errors in html. You can do so using captureErrors. The function has the following signature:
export interface ErrorSpan { name: string; attributes: Record<string, unknown>; durationInMilliseconds: number | undefined; startTime: bigint; endTime: bigint | undefined; } export interface ErrorData { errorType: unknown; message: unknown; stack: string[] | undefined; sources: Omit<ErrorRelatedSources, '_tag'>[] | undefined; location: Omit<ErrorLocation, '_tag'>[] | undefined; spans: ErrorSpan[] | undefined; isPlainString: boolean; } export interface CapturedErrors { interrupted: boolean; errors: ErrorData[]; } export interface CaptureErrorsOptions { stripCwd?: boolean; } const captureErrors: <E>( cause: Cause<E>, options?: CaptureErrorsOptions ) => Effect.Effect<CapturedErrors, FsError, FileSystem>
You can use captureErrors like so:
import { captureErrors } from 'effect-errors'; import { NodeFileSystem } from '@effect/platform-node'; await Effect.runPromise( pipe( effect, Effect.sandbox, Effect.catchAll((e) => Effect.gen(function* () { const errors = yield* captureErrors(e); // ... }), ), Effect.provide(NodeFileSystem.layer), ), );
Capturing errors from the from-promise bundle would return something like this, for example:
{
"interrupted": false,
"errors": [
{
"errorType": "FetchError",
"message": {
"code": "ConnectionRefused",
"path": "https://yolo-bro-oh-no.org/users/123",
"errno": 0
},
"stack": [
"at new e (:1:28)",
"at new <anonymous> (./src/tests/bundle/from-promise.js:31:85172)",
"at new t (:1:28)",
"at new Ga (:1:28)",
"at catch (./src/tests/bundle/from-promise.js:37:352)",
"at Sync (./src/tests/bundle/from-promise.js:31:39923)",
"at runLoop (./src/tests/bundle/from-promise.js:31:42686)",
"at evaluateEffect (./src/tests/bundle/from-promise.js:31:38196)",
"at evaluateMessageWhileSuspended (./src/tests/bundle/from-promise.js:31:37872)",
"at drainQueueOnCurrentThread (./src/tests/bundle/from-promise.js:31:35561)",
"at run (./src/tests/bundle/from-promise.js:31:43020)",
"at starveInternal (./src/tests/bundle/from-promise.js:31:6243)",
"at processTicksAndRejections (:12:39)"
],
"sources": [
{
"name": "FetchError",
"runPath": "/Users/jpb06/repos/perso/effect-errors/src/tests/bundle/from-promise.js:37:352",
"sourcesPath": "/Users/jpb06/repos/perso/effect-errors/src/examples/from-promise.ts:30:13",
"source": [
{
"line": 27,
"code": " try: async () =>"
},
{
"line": 28,
"code": " await fetch(`https://yolo-bro-oh-no.org/users/${userId}`),"
},
{
"line": 29,
"code": " catch: (e) =>"
},
{
"line": 30,
"code": " new FetchError({",
"column": 13
},
{
"line": 31,
"code": " cause: e,"
},
{
"line": 32,
"code": " }),"
},
{
"line": 33,
"code": " }),"
}
]
},
{
"name": "fetchTask",
"runPath": "/Users/jpb06/repos/perso/effect-errors/src/tests/bundle/from-promise.js:37:213",
"sourcesPath": "/Users/jpb06/repos/perso/effect-errors/src/examples/from-promise.ts:25:10",
"source": [
{
"line": 22,
"code": ");"
},
{
"line": 23,
"code": ""
},
{
"line": 24,
"code": "const fetchTask = (userId: string) =>"
},
{
"line": 25,
"code": " Effect.withSpan('fetch-user', { attributes: { userId } })(",
"column": 10
},
{
"line": 26,
"code": " Effect.tryPromise({"
},
{
"line": 27,
"code": " try: async () =>"
},
{
"line": 28,
"code": " await fetch(`https://yolo-bro-oh-no.org/users/${userId}`),"
}
]
},
{
"name": "fromPromiseTask",
"runPath": "/Users/jpb06/repos/perso/effect-errors/src/tests/bundle/from-promise.js:37:490",
"sourcesPath": "/Users/jpb06/repos/perso/effect-errors/src/examples/from-promise.ts:44:39",
"source": [
{
"line": 41,
"code": " }),"
},
{
"line": 42,
"code": " );"
},
{
"line": 43,
"code": ""
},
{
"line": 44,
"code": "export const fromPromiseTask = Effect.withSpan('from-promise-task')(",
"column": 39
},
{
"line": 45,
"code": " Effect.gen(function* () {"
},
{
"line": 46,
"code": " yield* filename(fileName);"
},
{
"line": 47,
"code": ""
}
]
}
],
"spans": [
{
"name": "fromPromiseTask",
"attributes": {},
"durationInMilliseconds": 246
},
{
"name": "fetchUser",
"attributes": {
"userId": "123"
},
"durationInMilliseconds": 239
}
],
"isPlainString": false
}
]
}If no map file is found, a location array will be returned instead of sources:
{
"interrupted": false,
"errors": [
{
"errorType": "FetchError",
"message": "request to https://yolo-bro-oh-no.org/users/1 failed, reason: getaddrinfo ENOTFOUND yolo-bro-oh-no.org",
"stack": [
"at catch (file:///Users/jpb06/repos/remix-effect-errors/build/server/nodejs-eyJydW50aW1lIjoibm9kZWpzIn0/index.js?t=1729013117205.3699:2:14550)",
"at EffectPrimitive.effect_instruction_i0 (file:///Users/jpb06/repos/remix-effect-errors/node_modules/effect/src/internal/core-effect.ts:1694:56)",
"at body (file:///Users/jpb06/repos/remix-effect-errors/node_modules/effect/src/internal/fiberRuntime.ts:1113:41)",
"at Object.effect_internal_function (file:///Users/jpb06/repos/remix-effect-errors/node_modules/effect/src/Utils.ts:780:14)",
"at internalCall (file:///Users/jpb06/repos/remix-effect-errors/node_modules/effect/src/Utils.ts:784:22)",
"at FiberRuntime.Sync (file:///Users/jpb06/repos/remix-effect-errors/node_modules/effect/src/internal/fiberRuntime.ts:1113:19)",
"at f (file:///Users/jpb06/repos/remix-effect-errors/node_modules/effect/src/internal/fiberRuntime.ts:1347:53)",
"at Object.context (file:///Users/jpb06/repos/remix-effect-errors/node_modules/effect/src/internal/tracer.ts:93:19)",
"at FiberRuntime.runLoop (file:///Users/jpb06/repos/remix-effect-errors/node_modules/effect/src/internal/fiberRuntime.ts:1337:34)",
"at FiberRuntime.evaluateEffect (file:///Users/jpb06/repos/remix-effect-errors/node_modules/effect/src/internal/fiberRuntime.ts:900:27)"
],
"location": [
{
"filePath": "/build/server/nodejs-eyJydW50aW1lIjoibm9kZWpzIn0/index.js",
"line": 2,
"column": 14414
},
{
"filePath": "/build/server/nodejs-eyJydW50aW1lIjoibm9kZWpzIn0/index.js",
"line": 2,
"column": 14703
},
{
"filePath": "/build/server/nodejs-eyJydW50aW1lIjoibm9kZWpzIn0/index.js",
"line": 2,
"column": 17636
}
],
"spans": [
{
"name": "fetch-user",
"attributes": {
"userId": 1
},
"durationInMilliseconds": 52
},
{
"name": "from-promise-task",
"attributes": {},
"durationInMilliseconds": 54
},
{
"name": "promise-example-loader",
"attributes": {
"url": "http://localhost:3000/promise",
"method": "GET",
"body": null
},
"durationInMilliseconds": 55
}
],
"isPlainString": false
}
]
}I wrote some examples for fun and giggles. You can run them using:
pnpm run-examples
You can check this example using remix error boundaries.