Programming doesn't need a lot of power, so a Macbook Air would be powerful enough.
You have basically 2 options. A 13" Macbook Air with 256gb SSD and 8gb of Ram, or a 13" Macbook Pro with 256gb SSD and 8GB of ram.
Macbook Pro has much better screen, a little bit faster, and it's a bit thicker and has worse battery life than the Air, and it's $1500
Macbook Air has a much better battery life, it's thinner, but it's a little bit slower and the screen isn't retina, but it's also $200 cheaper at $1300