There is only one language, but as imperfect students we have imperfect control of that language. We are like zoologists in the dark – one person holds a tail, one person holds a trunk, and another part of an ear. The well studied know full well what beast is present, but its wholeness is too great, and too tempremental to grasp all at once. The task then becomes to grasp an adequate portion of the beast so that profitable work can be done, while avoiding being crushed by its greatness.

Disciple seeks to grasp a portion of the one language that has not yet been adequately grasped. Disciple does not seek to be a new language, because there is only one language. Disciple provides a way to express and transform programs written in the (hopefully adequate) portion of the one language that it manages to grasp.

The portion of the one language that has been grasped is System-F2 with algebraic data, region types and modal effects. We believe these portions are the body, the feet, and perhaps the tusks of the beast. We dare not reach for more while our situation is still so tenuous.