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Try DataType for typescript, encoded as a class for Fluent API usage. (unsafe by spec 
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| type TryADT <E, A> = | |
| | { readonly _tag: "success", readonly success: A } | |
| | { readonly _tag: "failure", readonly failure: E } | |
| const success = <E, A>(successValue: A): TryADT<E, A> => ({ _tag: "success", success: successValue }) | |
| const failure = <E, A>(failureValue: E): TryADT<E, A> => ({ _tag: "failure", failure: failureValue }) | |
| class Try<E = never, A = never> { | |
| internalValue!: TryADT<E, A> | |
| private constructor( | |
| value: TryADT<E, A> | |
| ) { | |
| this.internalValue = value | |
| } | |
| static of = <E, A>( | |
| computation: () => A, | |
| onError: (reason: any) => E | |
| ): Try<E, A> => { | |
| try { | |
| const result = computation() | |
| return new Try(success(result)) | |
| } catch (reason) { | |
| return new Try(failure(onError(reason))) | |
| } | |
| } | |
| getOrDefault = (def: A): A => { | |
| return this.fold( | |
| _ => def, | |
| successValue => successValue | |
| ) | |
| } | |
| fold = <B>(onFailure: (failure: E) => B, onSuccess: (a: A) => B): B => { | |
| if (this.internalValue._tag === "failure") { | |
| return onFailure(this.internalValue.failure) | |
| } else { | |
| return onSuccess(this.internalValue.success) | |
| } | |
| } | |
| map = <B>(f: (successValue: A) => B): Try<E, B> => { | |
| const adt = this.fold( | |
| failureValue => failure<E, B>(failureValue), | |
| successValue => success(f(successValue)) | |
| ) | |
| return new Try(adt) | |
| } | |
| orNull = (): A | null => { | |
| if (this.internalValue._tag === "failure") { | |
| return null | |
| } else { | |
| return this.internalValue.success | |
| } | |
| } | |
| recover = (recoveValue: A) => { | |
| const adt = this.fold( | |
| _ => success(recoveValue), | |
| successValue => success(successValue) | |
| ) | |
| return new Try(adt) | |
| } | |
| recoverWith = (tryableComputation: (failureValue: E) => Try<E, A>): Try<E, A> => { | |
| return this.fold( | |
| failureValue => tryableComputation(failureValue), | |
| successValue => this.map(_ => successValue) | |
| ) | |
| } | |
| unsafeRaiseFailure = () => { | |
| this.fold( | |
| failure => { throw failure }, | |
| _ => { throw new Error("unsafeRaiseFailure called without failure inside") } | |
| ) | |
| } | |
| } |
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