Visually appealing pipe operator in TypeScript:

import pipe from 'pipe-es';
import * as R from "remeda";

pipe("Hello world!")
  .ᐅ(R.toUpperCase())
  .ᐅ(R.split(""))
  .ᐅ(R.reverse())
  .ᐅ(R.join(""))
  .ᐅ(console.log);

With IDE autocompletion, the emoji method name (ᐅ) is not an issue.

Installation

npm i pipe-es or copy the source code to your repository:

export default function pipe<T>(value: T) {
  type AsyncAwareReturn<V> = ReturnType<
    typeof pipe<T extends Promise<unknown> ? Promise<V> : V>
  >;

  interface PipeFn<T> {
    <V>(fn: (value: Awaited<T>) => V): AsyncAwareReturn<V>;

    <V, P2>(
      fn: (value: Awaited<T>, arg: P2) => V,
      arg: P2,
    ): AsyncAwareReturn<V>;

    (): T;
  }

  return {
    /**
     * Pipe to a function provided as a first argument.
     * Call with no arguments to return the current value.
     */
    ᐅ: ((fn?: (x: T, ...args: unknown[]) => unknown, ...args: unknown[]) => {
      if (!fn) return value;

      const newValue =
        value instanceof Promise
          ? value.then((result: Awaited<T>) => fn(result, ...args))
          : fn(value, ...args);

      return pipe(newValue);
    }) as PipeFn<T>,
  };
}

API

To start a pipe call the pipe(initial_value) function with the initial value. Then call the ᐅ method that comes in three flavours:

1. If no parameters are provided, the method returns the current value:

   import pipe from 'pipe-es';
   import * as R from "remeda";
   
   const result = pipe("Hello world!")
     .ᐅ(R.toUpperCase())
     .ᐅ();
      
   console.log(result === "HELLO WORLD!"); // prints 'true'

2. Provide a transformer function to pipe current value through it:

   import pipe from 'pipe-es';
   import * as R from "remeda";
      
   const result = pipe("Hello world!")
     .ᐅ(R.toUpperCase())
     .ᐅ(R.split(""))

3. Optionally, provide 2nd parameter that will be passed to the transformer function.

   import pipe from 'pipe-es';
   
   // The two examples below are equivalent
   pipe("Hello world!")
     .ᐅ(log, "input");
   
   pipe("Hello world!")
     .ᐅ((value) => log(value, "input"));
      
   function log<V>(value: V, label?: string): V {
     const reset = "\x1b[0m";
     const green = "\x1b[32m";
     const labelArray: unknown[] = label ? [`${green}[${label}]${reset}`] : [];
     console.log(...labelArray.concat(value));
     return value;
   }

License

MIT