筆記 - Effect Essentials

const const divide: (a: number, b: number) => numberdivide = (a: numbera: number, b: numberb: number): number => {
  if (b: numberb === 0) {
    throw new 
var Error: ErrorConstructor
new (message?: string, options?: ErrorOptions) => Error (+1 overload)
Error('Cannot divide by zero')
  }
  return a: numbera / b: numberb
}

const 
const success: Effect.Effect<number, never, never>success = import EffectEffect.const succeed: <number>(value: number) => Effect.Effect<number, never, never>succeed(8964)
 

const 
const failure: Effect.Effect<never, Error, never>failure = import EffectEffect.const fail: <Error>(error: Error) => Effect.Effect<never, Error, never>fail(new 
var Error: ErrorConstructor
new (message?: string, options?: ErrorOptions) => Error (+1 overload)
Error('Something went wrong'))
 

const const divide: (a: number, b: number) => Effect.Effect<number, Error>divide = (a: numbera: number, b: numberb: number): import EffectEffect.interface Effect<out A, out E = never, out R = never>Effect<number, Error> =>
  b: numberb === 0
    ? import EffectEffect.const fail: <Error>(error: Error) => Effect.Effect<never, Error, never>fail(new 
var Error: ErrorConstructor
new (message?: string, options?: ErrorOptions) => Error (+1 overload)
Error('Cannot divide by zero'))
    : import EffectEffect.const succeed: <number>(value: number) => Effect.Effect<number, never, never>succeed(a: numbera / b: numberb)
 
const 
const resultEffect: Effect.Effect<number, Error, never>resultEffect = const divide: (a: number, b: number) => Effect.Effect<number, Error>divide(10, 2)
 

const const log: (message: string) => Effect.Effect<string, never, never>log = (message: stringmessage: string) =>
  import EffectEffect.const sync: <string>(evaluate: LazyArg<string>) => Effect.Effect<string, never, never>sync(() => {
    var console: Consoleconsole.Console.log(message?: any, ...optionalParams: any[]): void (+1 overload)log(message: stringmessage) // side effect
    return 'Hello, World!'
  })
 
const 
const program: Effect.Effect<string, never, never>program = const log: (message: string) => Effect.Effect<string, never, never>log('Hello, World!')
 

const const parse: (input: string) => Effect.Effect<any, Error, never>parse = (input: stringinput: string) =>
  import EffectEffect.
try<any, Error>(options: {
    readonly try: LazyArg<any>;
    readonly catch: (error: unknown) => Error;
}): Effect.Effect<any, Error, never> (+1 overload)
export try
try({
    try: LazyArg<any>try: () => var JSON: JSONJSON.JSON.parse(text: string, reviver?: (this: any, key: string, value: any) => any): anyparse(input: stringinput),
    catch: (error: unknown) => Errorcatch: (unknown: unknownunknown) => new 
var Error: ErrorConstructor
new (message?: string, options?: ErrorOptions) => Error (+1 overload)
Error(`something went wrong ${unknown: unknownunknown}`)
  })
 
const 
const program: Effect.Effect<any, Error, never>program = const parse: (input: string) => Effect.Effect<any, Error, never>parse('')
 

const const delay: (message: string) => Effect.Effect<string, never, never>delay = (message: stringmessage: string) =>
  import EffectEffect.const promise: <string>(evaluate: (signal: AbortSignal) => PromiseLike<string>) => Effect.Effect<string, never, never>promise<string>(
    () =>
      new 
var Promise: PromiseConstructor
new <string>(executor: (resolve: (value: string | PromiseLike<string>) => void, reject: (reason?: any) => void) => void) => Promise<string>
Promise((resolve: (value: string | PromiseLike<string>) => voidresolve) => {
        function setTimeout<[]>(callback: () => void, ms?: number): NodeJS.Timeout (+2 overloads)setTimeout(() => {
          resolve: (value: string | PromiseLike<string>) => voidresolve(message: stringmessage)
        }, 2000)
      })
  )
 
const 
const program: Effect.Effect<string, never, never>program = const delay: (message: string) => Effect.Effect<string, never, never>delay('Async operation completed successfully!')
 

const const getTodo: (id: number) => Effect.Effect<Response, Error, never>getTodo = (id: numberid: number) =>
  import EffectEffect.
const tryPromise: <Response, Error>(options: {
    readonly try: (signal: AbortSignal) => PromiseLike<Response>;
    readonly catch: (error: unknown) => Error;
}) => Effect.Effect<...> (+1 overload)
tryPromise({
    try: (signal: AbortSignal) => PromiseLike<Response>try: () => function fetch(input: string | URL | globalThis.Request, init?: RequestInit): Promise<Response> (+1 overload)fetch(`https://jsonplaceholder.typicode.com/todos/${id: numberid}`),
    catch: (error: unknown) => Errorcatch: (unknown: unknownunknown) => new 
var Error: ErrorConstructor
new (message?: string, options?: ErrorOptions) => Error (+1 overload)
Error(`something went wrong ${unknown: unknownunknown}`)
  })
 
const 
const program: Effect.Effect<Response, Error, never>program = const getTodo: (id: number) => Effect.Effect<Response, Error, never>getTodo(1)
 

const const readFile: (filename: string) => Effect.Effect<Buffer, Error, never>readFile = (filename: stringfilename: string) =>
  import EffectEffect.const async: <Buffer, Error, never>(register: (callback: (_: Effect.Effect<Buffer, Error, never>) => void, signal: AbortSignal) => void | Effect.Effect<void, never, never>, blockingOn?: FiberId) => Effect.Effect<...>async<Buffer, Error>((resume: (_: Effect.Effect<Buffer, Error, never>) => voidresume) => {
    module "node:fs"NodeFS.function readFile(path: NodeFS.PathOrFileDescriptor, callback: (err: NodeJS.ErrnoException | null, data: Buffer) => void): void (+3 overloads)readFile(filename: stringfilename, (error: NodeJS.ErrnoException | nullerror, data: Bufferdata) => {
      if (error: NodeJS.ErrnoException | nullerror) {
        resume: (_: Effect.Effect<Buffer, Error, never>) => voidresume(import EffectEffect.const fail: <NodeJS.ErrnoException>(error: NodeJS.ErrnoException) => Effect.Effect<never, NodeJS.ErrnoException, never>fail(error: NodeJS.ErrnoExceptionerror))
      } else {
        resume: (_: Effect.Effect<Buffer, Error, never>) => voidresume(import EffectEffect.const succeed: <Buffer>(value: Buffer) => Effect.Effect<Buffer, never, never>succeed(data: Bufferdata))
      }
    })
  })
 
const 
const program: Effect.Effect<Buffer, Error, never>program = const readFile: (filename: string) => Effect.Effect<Buffer, Error, never>readFile("todos.txt")
 

// === Lazy Evaluation ===
 
let let i: numberi = 0
 
const const badEffect: Effect.Effect<number, never, never>badEffect = import EffectEffect.const succeed: <number>(value: number) => Effect.Effect<number, never, never>succeed(let i: numberi++)
const const goodEffect: Effect.Effect<number, never, never>goodEffect = import EffectEffect.const suspend: <number, never, never>(effect: LazyArg<Effect.Effect<number, never, never>>) => Effect.Effect<number, never, never>suspend(() => import EffectEffect.const succeed: <number>(value: number) => Effect.Effect<number, never, never>succeed(let i: numberi++))
 
import EffectEffect.const runSync: <number, never>(effect: Effect.Effect<number, never, never>) => numberrunSync(const badEffect: Effect.Effect<number, never, never>badEffect) // Output: 0
import EffectEffect.const runSync: <number, never>(effect: Effect.Effect<number, never, never>) => numberrunSync(const badEffect: Effect.Effect<number, never, never>badEffect) // Output: 0
 
import EffectEffect.const runSync: <number, never>(effect: Effect.Effect<number, never, never>) => numberrunSync(const goodEffect: Effect.Effect<number, never, never>goodEffect) // Output: 1
import EffectEffect.const runSync: <number, never>(effect: Effect.Effect<number, never, never>) => numberrunSync(const goodEffect: Effect.Effect<number, never, never>goodEffect) // Output: 2

// === Handling Circular Dependencies ===
 
const const blowsUp: (n: number) => Effect.Effect<number>blowsUp = (n: numbern: number): import EffectEffect.interface Effect<out A, out E = never, out R = never>Effect<number> =>
  n: numbern < 2
    ? import EffectEffect.const succeed: <number>(value: number) => Effect.Effect<number, never, never>succeed(1)
    : import EffectEffect.
const zipWith: <number, never, never, number, never, never, number>(self: Effect.Effect<number, never, never>, that: Effect.Effect<number, never, never>, f: (a: number, b: number) => number, options?: {
    readonly concurrent?: boolean | undefined;
    readonly batching?: boolean | "inherit" | undefined;
    readonly concurrentFinalizers?: boolean | undefined;
}) => Effect.Effect<...> (+1 overload)
zipWith(const blowsUp: (n: number) => Effect.Effect<number>blowsUp(n: numbern - 1), const blowsUp: (n: number) => Effect.Effect<number>blowsUp(n: numbern - 2), (a: numbera, b: numberb) => a: numbera + b: numberb)
 
import EffectEffect.const runSync: <number, never>(effect: Effect.Effect<number, never, never>) => numberrunSync(const blowsUp: (n: number) => Effect.Effect<number>blowsUp(32)) // crash: JavaScript heap out of memory
 
const const allGood: (n: number) => Effect.Effect<number>allGood = (n: numbern: number): import EffectEffect.interface Effect<out A, out E = never, out R = never>Effect<number> =>
  n: numbern < 2
    ? import EffectEffect.const succeed: <number>(value: number) => Effect.Effect<number, never, never>succeed(1)
    : import EffectEffect.
const zipWith: <number, never, never, number, never, never, number>(self: Effect.Effect<number, never, never>, that: Effect.Effect<number, never, never>, f: (a: number, b: number) => number, options?: {
    readonly concurrent?: boolean | undefined;
    readonly batching?: boolean | "inherit" | undefined;
    readonly concurrentFinalizers?: boolean | undefined;
}) => Effect.Effect<...> (+1 overload)
zipWith(
        import EffectEffect.const suspend: <number, never, never>(effect: LazyArg<Effect.Effect<number, never, never>>) => Effect.Effect<number, never, never>suspend(() => const allGood: (n: number) => Effect.Effect<number>allGood(n: numbern - 1)),
        import EffectEffect.const suspend: <number, never, never>(effect: LazyArg<Effect.Effect<number, never, never>>) => Effect.Effect<number, never, never>suspend(() => const allGood: (n: number) => Effect.Effect<number>allGood(n: numbern - 2)),
        (a: numbera, b: numberb) => a: numbera + b: numberb
      )
 
import EffectEffect.const runSync: <number, never>(effect: Effect.Effect<number, never, never>) => numberrunSync(const allGood: (n: number) => Effect.Effect<number>allGood(32)) // Output: 3524578

// === Unifying Return Type ===
 
const const ugly: (a: number, b: number) => Effect.Effect<never, Error, never> | Effect.Effect<number, never, never>ugly = (a: numbera: number, b: numberb: number) =>
  b: numberb === 0
    ? import EffectEffect.const fail: <Error>(error: Error) => Effect.Effect<never, Error, never>fail(new 
var Error: ErrorConstructor
new (message?: string, options?: ErrorOptions) => Error (+1 overload)
Error("Cannot divide by zero"))
    : import EffectEffect.const succeed: <number>(value: number) => Effect.Effect<number, never, never>succeed(a: numbera / b: numberb)
 
const const nice: (a: number, b: number) => Effect.Effect<number, Error, never>nice = (a: numbera: number, b: numberb: number) =>
  import EffectEffect.const suspend: <number, Error, never>(effect: LazyArg<Effect.Effect<number, Error, never>>) => Effect.Effect<number, Error, never>suspend(() =>
    b: numberb === 0
      ? import EffectEffect.const fail: <Error>(error: Error) => Effect.Effect<never, Error, never>fail(new 
var Error: ErrorConstructor
new (message?: string, options?: ErrorOptions) => Error (+1 overload)
Error("Cannot divide by zero"))
      : import EffectEffect.const succeed: <number>(value: number) => Effect.Effect<number, never, never>succeed(a: numbera / b: numberb)
  )

const const program: Effect.Effect<number, never, never>program = import EffectEffect.const sync: <number>(evaluate: LazyArg<number>) => Effect.Effect<number, never, never>sync(() => {
  var console: Consoleconsole.Console.log(message?: any, ...optionalParams: any[]): void (+1 overload)log("Hello, World!")
  return 1
})
 
const const result: numberresult = import EffectEffect.const runSync: <number, never>(effect: Effect.Effect<number, never, never>) => numberrunSync(const program: Effect.Effect<number, never, never>program)
// Output: Hello, World!
 
var console: Consoleconsole.Console.log(message?: any, ...optionalParams: any[]): void (+1 overload)log(const result: numberresult)
// Output: 1

const const result1: Exit<number, never>result1 = import EffectEffect.const runSyncExit: <number, never>(effect: Effect.Effect<number, never, never>) => Exit<number, never>runSyncExit(import EffectEffect.const succeed: <number>(value: number) => Effect.Effect<number, never, never>succeed(1))
var console: Consoleconsole.Console.log(message?: any, ...optionalParams: any[]): void (+1 overload)log(const result1: Exit<number, never>result1)
/*
  Output:
  {
    _id: "Exit",
    _tag: "Success",
    value: 1
  }
*/
 
const const result2: Exit<never, string>result2 = import EffectEffect.const runSyncExit: <never, string>(effect: Effect.Effect<never, string, never>) => Exit<never, string>runSyncExit(import EffectEffect.const fail: <string>(error: string) => Effect.Effect<never, string, never>fail("my error"))
var console: Consoleconsole.Console.log(message?: any, ...optionalParams: any[]): void (+1 overload)log(const result2: Exit<never, string>result2)
/*
  Output:
  {
    _id: "Exit",
    _tag: "Failure",
    cause: {
      _id: "Cause",
      _tag: "Fail",
      failure: "my error"
    }
  }
*/

import EffectEffect.
const runPromise: <number, never>(effect: Effect.Effect<number, never, never>, options?: {
    readonly signal?: AbortSignal;
} | undefined) => Promise<number>
runPromise(import EffectEffect.const succeed: <number>(value: number) => Effect.Effect<number, never, never>succeed(1)).Promise<number>.then<void, never>(onfulfilled?: ((value: number) => void | PromiseLike<void>) | null | undefined, onrejected?: ((reason: any) => PromiseLike<never>) | null | undefined): Promise<...>then(var console: Consoleconsole.Console.log(...data: any[]): void (+1 overload)log) // Output: 1
 
import EffectEffect.
const runPromise: <never, string>(effect: Effect.Effect<never, string, never>, options?: {
    readonly signal?: AbortSignal;
} | undefined) => Promise<never>
runPromise(import EffectEffect.const fail: <string>(error: string) => Effect.Effect<never, string, never>fail("my error")) // rejects

import EffectEffect.
const runPromiseExit: <number, never>(effect: Effect.Effect<number, never, never>, options?: {
    readonly signal?: AbortSignal;
} | undefined) => Promise<Exit<number, never>>
runPromiseExit(import EffectEffect.const succeed: <number>(value: number) => Effect.Effect<number, never, never>succeed(1)).Promise<Exit<number, never>>.then<void, never>(onfulfilled?: ((value: Exit<number, never>) => void | PromiseLike<void>) | null | undefined, onrejected?: ((reason: any) => PromiseLike<never>) | null | undefined): Promise<...>then(var console: Consoleconsole.Console.log(...data: any[]): void (+1 overload)log)
/*
  Output:
  {
    _id: "Exit",
    _tag: "Success",
    value: 1
  }
*/
 
import EffectEffect.
const runPromiseExit: <never, string>(effect: Effect.Effect<never, string, never>, options?: {
    readonly signal?: AbortSignal;
} | undefined) => Promise<Exit<never, string>>
runPromiseExit(import EffectEffect.const fail: <string>(error: string) => Effect.Effect<never, string, never>fail("my error")).Promise<Exit<never, string>>.then<void, never>(onfulfilled?: ((value: Exit<never, string>) => void | PromiseLike<void>) | null | undefined, onrejected?: ((reason: any) => PromiseLike<never>) | null | undefined): Promise<...>then(var console: Consoleconsole.Console.log(...data: any[]): void (+1 overload)log)
/*
  Output:
  {
    _id: "Exit",
    _tag: "Failure",
    cause: {
      _id: "Cause",
      _tag: "Fail",
      failure: "my error"
    }
  }
*/

import { import EffectEffect, import ConsoleConsole, import ScheduleSchedule, import FiberFiber } from "effect"
 
const const program: Effect.Effect<number, never, never>program = import EffectEffect.const repeat: <void, never, never, number, never>(self: Effect.Effect<void, never, never>, schedule: Schedule.Schedule<number, void, never>) => Effect.Effect<number, never, never> (+3 overloads)repeat(
  import ConsoleConsole.const log: (...args: ReadonlyArray<any>) => Effect.Effect<void>log("running..."),
  import ScheduleSchedule.const spaced: (duration: DurationInput) => Schedule.Schedule<number>spaced("200 millis")
)
 
const const fiber: Fiber.RuntimeFiber<number, never>fiber = import EffectEffect.const runFork: <number, never>(effect: Effect.Effect<number, never, never>, options?: RunForkOptions) => Fiber.RuntimeFiber<number, never>runFork(const program: Effect.Effect<number, never, never>program)
 
function setTimeout<[]>(callback: () => void, ms?: number): NodeJS.Timeout (+2 overloads)setTimeout(() => {
  import EffectEffect.const runFork: <Exit<number, never>, never>(effect: Effect.Effect<Exit<number, never>, never, never>, options?: RunForkOptions) => Fiber.RuntimeFiber<...>runFork(import FiberFiber.const interrupt: <number, never>(self: Fiber.Fiber<number, never>) => Effect.Effect<Exit<number, never>, never, never>interrupt(const fiber: Fiber.RuntimeFiber<number, never>fiber))
}, 500)

// Function to add a small service charge to a transaction amount
const const addServiceCharge: (amount: number) => numberaddServiceCharge = (amount: numberamount: number) => amount: numberamount + 1
 
// Function to apply a discount safely to a transaction amount
const const applyDiscount: (total: number, discountRate: number) => Effect.Effect<number, Error>applyDiscount = (
  total: numbertotal: number,
  discountRate: numberdiscountRate: number
): import EffectEffect.interface Effect<out A, out E = never, out R = never>Effect<number, Error> =>
  discountRate: numberdiscountRate === 0
    ? import EffectEffect.const fail: <Error>(error: Error) => Effect.Effect<never, Error, never>fail(new 
var Error: ErrorConstructor
new (message?: string, options?: ErrorOptions) => Error (+1 overload)
Error("Discount rate cannot be zero"))
    : import EffectEffect.const succeed: <number>(value: number) => Effect.Effect<number, never, never>succeed(total: numbertotal - (total: numbertotal * discountRate: numberdiscountRate) / 100)
 
// Simulated asynchronous task to fetch a transaction amount from a database
const const fetchTransactionAmount: Effect.Effect<number, never, never>fetchTransactionAmount = import EffectEffect.const promise: <number>(evaluate: (signal: AbortSignal) => PromiseLike<number>) => Effect.Effect<number, never, never>promise(() => var Promise: PromiseConstructorPromise.PromiseConstructor.resolve<number>(value: number): Promise<number> (+2 overloads)resolve(100))
 
// Simulated asynchronous task to fetch a discount rate from a configuration file
const const fetchDiscountRate: Effect.Effect<number, never, never>fetchDiscountRate = import EffectEffect.const promise: <number>(evaluate: (signal: AbortSignal) => PromiseLike<number>) => Effect.Effect<number, never, never>promise(() => var Promise: PromiseConstructorPromise.PromiseConstructor.resolve<number>(value: number): Promise<number> (+2 overloads)resolve(5))
 
// Assembling the program using a generator function
const const program: Effect.Effect<string, Error, never>program = import EffectEffect.const gen: <YieldWrap<Effect.Effect<number, Error, never>>, string>(f: (resume: Effect.Adapter) => Generator<YieldWrap<Effect.Effect<number, Error, never>>, string, never>) => Effect.Effect<...> (+1 overload)gen(function* () {
  // Retrieve the transaction amount
  const const transactionAmount: numbertransactionAmount = yield* const fetchTransactionAmount: Effect.Effect<number, never, never>fetchTransactionAmount
 
  // Retrieve the discount rate
  const const discountRate: numberdiscountRate = yield* const fetchDiscountRate: Effect.Effect<number, never, never>fetchDiscountRate
 
  // Calculate discounted amount
  const const discountedAmount: numberdiscountedAmount = yield* const applyDiscount: (total: number, discountRate: number) => Effect.Effect<number, Error>applyDiscount(
    const transactionAmount: numbertransactionAmount,
    const discountRate: numberdiscountRate
  )
 
  // Apply service charge
  const const finalAmount: numberfinalAmount = const addServiceCharge: (amount: number) => numberaddServiceCharge(const discountedAmount: numberdiscountedAmount)
 
  // Return the total amount after applying the charge
  return `Final amount to charge: ${const finalAmount: numberfinalAmount}`
})
 
// Execute the program and log the result
import EffectEffect.
const runPromise: <string, Error>(effect: Effect.Effect<string, Error, never>, options?: {
    readonly signal?: AbortSignal;
} | undefined) => Promise<string>
runPromise(const program: Effect.Effect<string, Error, never>program).Promise<string>.then<void, never>(onfulfilled?: ((value: string) => void | PromiseLike<void>) | null | undefined, onrejected?: ((reason: any) => PromiseLike<never>) | null | undefined): Promise<...>then(var console: Consoleconsole.Console.log(...data: any[]): void (+1 overload)log) // Output: "Final amount to charge: 96"

import { function pipe<A>(a: A): A (+19 overloads)pipe } from "effect"
 
const const increment: (x: number) => numberincrement = (x: numberx: number) => x: numberx + 1
const const double: (x: number) => numberdouble = (x: numberx: number) => x: numberx * 2
const const subtractTen: (x: number) => numbersubtractTen = (x: numberx: number) => x: numberx - 10
 
const const result: numberresult = pipe<5, number, number, number>(a: 5, ab: (a: 5) => number, bc: (b: number) => number, cd: (c: number) => number): number (+19 overloads)pipe(5, const increment: (x: number) => numberincrement, const double: (x: number) => numberdouble, const subtractTen: (x: number) => numbersubtractTen)
 
var console: Consoleconsole.Console.log(message?: any, ...optionalParams: any[]): void (+1 overload)log(const result: numberresult) // Output: 2

import { function pipe<A>(a: A): A (+19 overloads)pipe, import EffectEffect } from "effect"
 
// Function to add a small service charge to a transaction amount
const const addServiceCharge: (amount: number) => numberaddServiceCharge = (amount: numberamount: number) => amount: numberamount + 1
 
// Simulated asynchronous task to fetch a transaction amount from a database
const const fetchTransactionAmount: Effect.Effect<number, never, never>fetchTransactionAmount = import EffectEffect.const promise: <number>(evaluate: (signal: AbortSignal) => PromiseLike<number>) => Effect.Effect<number, never, never>promise(() => var Promise: PromiseConstructorPromise.PromiseConstructor.resolve<number>(value: number): Promise<number> (+2 overloads)resolve(100))
 
// Apply service charge to the transaction amount
const const finalAmount: Effect.Effect<number, never, never>finalAmount = pipe<Effect.Effect<number, never, never>, Effect.Effect<number, never, never>>(a: Effect.Effect<number, never, never>, ab: (a: Effect.Effect<number, never, never>) => Effect.Effect<...>): Effect.Effect<...> (+19 overloads)pipe(const fetchTransactionAmount: Effect.Effect<number, never, never>fetchTransactionAmount, import EffectEffect.const map: <number, number>(f: (a: number) => number) => <E, R>(self: Effect.Effect<number, E, R>) => Effect.Effect<number, E, R> (+1 overload)map(const addServiceCharge: (amount: number) => numberaddServiceCharge))
 
import EffectEffect.
const runPromise: <number, never>(effect: Effect.Effect<number, never, never>, options?: {
    readonly signal?: AbortSignal;
} | undefined) => Promise<number>
runPromise(const finalAmount: Effect.Effect<number, never, never>finalAmount).Promise<number>.then<void, never>(onfulfilled?: ((value: number) => void | PromiseLike<void>) | null | undefined, onrejected?: ((reason: any) => PromiseLike<never>) | null | undefined): Promise<...>then(var console: Consoleconsole.Console.log(...data: any[]): void (+1 overload)log) // Output: 101

const mappedEffect = pipe(myEffect, Effect.map(transformation))
 
const mappedEffect = Effect.map(myEffect, transformation)
 
const mappedEffect = myEffect.pipe(Effect.map(transformation))

import { function pipe<A>(a: A): A (+19 overloads)pipe, import EffectEffect } from "effect"
 
// Function to apply a discount safely to a transaction amount
const const applyDiscount: (total: number, discountRate: number) => Effect.Effect<number, Error>applyDiscount = (
  total: numbertotal: number,
  discountRate: numberdiscountRate: number
): import EffectEffect.interface Effect<out A, out E = never, out R = never>Effect<number, Error> =>
  discountRate: numberdiscountRate === 0
    ? import EffectEffect.const fail: <Error>(error: Error) => Effect.Effect<never, Error, never>fail(new 
var Error: ErrorConstructor
new (message?: string, options?: ErrorOptions) => Error (+1 overload)
Error("Discount rate cannot be zero"))
    : import EffectEffect.const succeed: <number>(value: number) => Effect.Effect<number, never, never>succeed(total: numbertotal - (total: numbertotal * discountRate: numberdiscountRate) / 100)
 
// Simulated asynchronous task to fetch a transaction amount from a database
const const fetchTransactionAmount: Effect.Effect<number, never, never>fetchTransactionAmount = import EffectEffect.const promise: <number>(evaluate: (signal: AbortSignal) => PromiseLike<number>) => Effect.Effect<number, never, never>promise(() => var Promise: PromiseConstructorPromise.PromiseConstructor.resolve<number>(value: number): Promise<number> (+2 overloads)resolve(100))
 
const const finalAmount: Effect.Effect<number, Error, never>finalAmount = pipe<Effect.Effect<number, never, never>, Effect.Effect<number, Error, never>>(a: Effect.Effect<number, never, never>, ab: (a: Effect.Effect<number, never, never>) => Effect.Effect<...>): Effect.Effect<...> (+19 overloads)pipe(
  const fetchTransactionAmount: Effect.Effect<number, never, never>fetchTransactionAmount,
  import EffectEffect.const flatMap: <number, number, Error, never>(f: (a: number) => Effect.Effect<number, Error, never>) => <E, R>(self: Effect.Effect<number, E, R>) => Effect.Effect<number, Error | E, R> (+1 overload)flatMap((amount: numberamount) => const applyDiscount: (total: number, discountRate: number) => Effect.Effect<number, Error>applyDiscount(amount: numberamount, 5))
)
 
import EffectEffect.
const runPromise: <number, Error>(effect: Effect.Effect<number, Error, never>, options?: {
    readonly signal?: AbortSignal;
} | undefined) => Promise<number>
runPromise(const finalAmount: Effect.Effect<number, Error, never>finalAmount).Promise<number>.then<void, never>(onfulfilled?: ((value: number) => void | PromiseLike<void>) | null | undefined, onrejected?: ((reason: any) => PromiseLike<never>) | null | undefined): Promise<...>then(var console: Consoleconsole.Console.log(...data: any[]): void (+1 overload)log) // Output: 95