Re: Seeking brief description of the benefits of Type Inference

David Witten <david.witten@template.com> wrote:
|> I don't know ML (or any other language that has type inference), and so
|> don't know why type inference is good. Other than obviating the need
|> to declare the type of constructs what are the benefits of it to the
|> work-a-day programmer/maintainer?


As an example of type inference used outside of ML, C++ uses type
inference to instantiate function templates. Consider the following
C++ function template:


        template <class T>
        void insert0(T a[], T *b)
        {
T temp;
temp = *b;
a[0] = temp;
        }


This function could be called with the statements:


        int k=20;
        int i[10] = {10, 9, 8, 7, 6, 5, 4, 3, 2, 1}, *j=&k;


        insert0(i,j);


When the function insert0 is invoked, C++ will use the type of the
actual arguments to infer the type of the local variable temp. In
this case it will infer that temp has type "int."


|> Could someone tell me an on-line reference that will answer my
|> question?


I don't know of an on-line reference, but the book "Compilers:
Principles, Techniques and Tools" by Aho, Sethi, and Ullman gives an
introduction to type inference in sections 6.6 & 6.7, along with
references to other works.


--
Daniel J. Salomon -- salomon@cs.UManitoba.CA
              Dept. of Computer Science / University of Manitoba
              Winnipeg, Manitoba, Canada R3T 2N2 / (204) 474-8687


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