M. Widera.
**An Algorithm for Checking the Disjointness of Types**.
In Manuel Serrano, editor, Proceedings of the Second Workshop
on Scheme and Functional Programming, 2001.

#### Abstract:

We describe an algorithm approximating the following
question: Given two types t1 and t2, are there instances
sigma(t1) and sigma(t2) denoting a common element? By answering
this question we solve a main problem towards a type checking
algorithm for non-disjoint types that raises an error just for
function calls that cannot be executed successfully for any
input arguments. For dynamically typed functional languages as
e.g. Scheme such a type checker can extend current soft typing
systems in order to reject provably ill-typed programs.

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