From Constructivism to Computer Science
A.S. Troelstra

Abstract:
My field is mathematical logic, with a special interest in constructivism,
and I would not dare to call myself a computer scientist. But some computer
scientists regard my work as a contribution to their field; and in this text I
shall try to explain how this is possible, by taking a look at the history of
ideas.
I want to describe how two interrelated ideas, connected with the constructi-
vistic trend in the foundations of mathematics, developed within mathematical 
logic and ultimately diffused into computer science.
It will be seen that this development has not been a quite straightforward
one. In the history of ideas it often looks as if a certain idea has to be
discovered several times, by different people, before it really enters into 
the ``consciousness'' of science.