Move Player with WASD keys (UniRx)

MoveWASD.cs

using System;
using System.Collections;
using UnityEngine;
using UniRx;
using UniRx.Triggers;

public class Player : MonoBehaviour {

	void Start() {
		Func<KeyCode, IObservable<Unit>> onGetKey = (keyCode) => this.UpdateAsObservable().Where(_ => Input.GetKey(keyCode));

		var forward = onGetKey(KeyCode.W).Select(_ => this.transform.forward);
		var back = onGetKey(KeyCode.S).Select(_ => -1 * this.transform.forward);
		var left = onGetKey(KeyCode.A).Select(_ => Vector3.Cross(this.transform.forward, this.transform.up));
		var right = onGetKey(KeyCode.D).Select(_ => -1 * Vector3.Cross(this.transform.forward, this.transform.up));

		forward.Merge(back).Subscribe(v => this.transform.position += v * Time.deltaTime);
		left.Merge(right).Subscribe(v => this.transform.forward = Vector3.Lerp(this.transform.forward, v, Time.deltaTime));
	}

}