Unity: dash & slide along wall

void Dash(Vector3 normalisedDirection)
{
    var position = transform.position;
    // assume the collider is a circle - if it's not it's a little more complicated
    var collider = GetComponent<CircleCollider2D>();

    // store only the first hit, we don't need the rest
    var results = new RaycastHit2D[1];
    // cast our rigidbody
    var hitCount = rbody.Cast(normalisedDirection, results, dashDistance);
    // if we didn't hit anything
    if (hitCount == 0)
    {
        // lerp between our current position and the new dash position
        StartCoroutine(DoDash(position,
            position + normalisedDirection * dashDistance, Vector3.zero, 1));
    }
    else // we hit something
    {
        // get the position minus the collider's radius (so we don't clip into the wall)
        var hitPoint = position + results[0].fraction * (dashDistance - collider.radius) * normalisedDirection;
        // get a vector that is perpendicular to the hit normal
        var perpendicular = new Vector2(results[0].normal.y, -results[0].normal.x);
        // cast a ray in that direction, to slide along the wall - but we only want to go a fraction of the way along our dash, not the entire distance
        var hit = Physics2D.Raycast(hitPoint, perpendicular, dashDistance - results[0].fraction * dashDistance);
        // lerp between the 3 positions
        StartCoroutine(DoDash(position, hitPoint, hit.point, results[0].fraction));

    }
}

IEnumerator DoDash(Vector3 startPos, Vector3 pos1, Vector3 pos2, float fraction)
{
    float t = 0;
    while (t < 1)
    {
        if (t < fraction)
            transform.position = Vector3.Lerp(startPos, pos1, t/fraction);
        else
            transform.position = Vector3.Lerp(pos1, pos2, (t - fraction)/(1-fraction));

        t += Time.deltaTime / dashTime;
        yield return null;
    }

    transform.position = Mathf.Approximately(fraction, 1) ? pos1 : pos2;
}