Can the set of computable numbers be used as a theoretical basis for calculus?
Solution 1:
You can see at least Constructive Mathematics from Douglas Bridges and google for : Douglas Bridges, Introducing Constructive Mathematics.
You can also read online D.Bridges' FAQ list on Constructive Mathematics.
For calculus, see :
Errett Bishop, Foundations of constructive analysis (1967).
Errett Bishop & Douglas Bridges, Constructive Analysis (1985).