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import type { Mapper, SideEffect, Supplier } from "@emprespresso/pengueno";
// the "thing" every Trace writer must "trace()"
type BaseTraceWith = string;
export type ITraceWith<T> = BaseTraceWith | T;
export interface ITrace<TraceWith> {
addTrace: Mapper<ITraceWith<TraceWith>, ITrace<TraceWith>>;
trace: SideEffect<ITraceWith<TraceWith>>;
}
export type ITraceableTuple<T, TraceWith> = [T, BaseTraceWith | TraceWith];
export type ITraceableMapper<
T,
U,
TraceWith,
W = ITraceable<T, TraceWith>,
> = (
w: W,
) => U;
export interface ITraceable<T, Trace = BaseTraceWith> {
readonly trace: ITrace<Trace>;
get: Supplier<T>;
move: <U>(u: U) => ITraceable<U, Trace>;
map: <U>(
mapper: ITraceableMapper<T, U, Trace>,
) => ITraceable<U, Trace>;
bimap: <U>(
mapper: ITraceableMapper<
T,
ITraceableTuple<U, Array<Trace> | Trace>,
Trace
>,
) => ITraceable<U, Trace>;
peek: (peek: ITraceableMapper<T, void, Trace>) => ITraceable<T, Trace>;
flatMap: <U>(
mapper: ITraceableMapper<T, ITraceable<U, Trace>, Trace>,
) => ITraceable<U, Trace>;
flatMapAsync<U>(
mapper: ITraceableMapper<T, Promise<ITraceable<U, Trace>>, Trace>,
): ITraceable<Promise<U>, Trace>;
}
export class TraceableImpl<T, TraceWith> implements ITraceable<T, TraceWith> {
protected constructor(
private readonly item: T,
public readonly trace: ITrace<TraceWith>,
) {}
public map<U>(
mapper: ITraceableMapper<T, U, TraceWith>,
) {
const result = mapper(this);
return new TraceableImpl(result, this.trace);
}
public flatMap<U>(
mapper: ITraceableMapper<
T,
ITraceable<U, TraceWith>,
TraceWith
>,
): ITraceable<U, TraceWith> {
return mapper(this);
}
public flatMapAsync<U>(
mapper: ITraceableMapper<
T,
Promise<ITraceable<U, TraceWith>>,
TraceWith
>,
): ITraceable<Promise<U>, TraceWith> {
return new TraceableImpl(
mapper(this).then((t) => t.get()),
this.trace,
);
}
public peek(peek: ITraceableMapper<T, void, TraceWith>) {
peek(this);
return this;
}
public move<Tt>(t: Tt): ITraceable<Tt, TraceWith> {
return this.map(() => t);
}
public bimap<U>(
mapper: ITraceableMapper<
T,
ITraceableTuple<U, Array<TraceWith> | TraceWith>,
TraceWith
>,
) {
const [item, trace] = mapper(this);
const traces = Array.isArray(trace) ? trace : [trace];
return new TraceableImpl(
item,
traces.reduce((trace, _trace) => trace.addTrace(_trace), this.trace),
);
}
public get() {
return this.item;
}
}
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