Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!umich!yale!cs.utexas.edu!usc!ucla-cs!uci-ics!srinivas
From: srinivas@ics.uci.edu (Yellamraju Srinivas)
Newsgroups: comp.object
Subject: Re: "Ad Hoc Polymorphism" -- I'm Quoting Someone Else
Keywords: ad hoc polymorphism, reference to original use
Message-ID: <25AA471B.5687@paris.ics.uci.edu>
Date: 9 Jan 90 20:18:34 GMT
References: <646@ajpo.sei.cmu.edu>
Lines: 40

eberard@ajpo.sei.cmu.edu (Edward Berard) writes:

>If you recognize this type of polymorphism as having a different name,
>and can cite two, or more, earlier references, I will consider using
>a different name. (Heck! I'll even take _one_ earlier reference. ;-))


Here is a quote from J. C. Reynolds [1]:

    The concept of polymorphism was first recognized by Strachey [2],
    who distinguished between "parametric" and "ad hoc" polymorphism.
    Intuitively, a parametric polymorphic function is one that behaves
    the same way for all types, while an ad hoc polymorphic function
    may have unrelated meanings for different tyupes. For example, an
    ad hoc function might add integers, "or" Boolean values, and
    compose functions.

"Ad hoc" polymorphism is another name for overloading, i.e, the use
the same syntactic symbol to denote different functions depending on
the context. The concept of "parametric polymorphism" is an intuitive
one.  Recently, there have attempts to characterize this notion
formally [3][4], by using the precise concepts of "functorial" and
"natural" in category theory.

[1] J.C.Reynolds, "Types, Abstraction and Parametric Polymorphism",
    Information Processing '83, Ed. R.E.A.Mason, North-Holland, 1983.
[2] C. Strachey, "Fundamental Concepts in Programming Languages",
    Lecture Notes, International Summer School in Computer
    Programming, Copenhagen, August 1967.
[3] E.S.Bainbridge, P.J.Freyd, A.Scedrov, and P.J.Scott, "Functorial
    Polymorphism", in "Logical Foundations of Functional Programming",
    Proceedings, Austin, 1987, Ed. G. Huet, Addison-Wesley, in press.
[4] P.J.Freyd, J.Y.Girard, A.Scedrov, and P.J.Scott, "Semantic
    Parametricity in Polymorphic Lambda Calculus", in Proceedings,
    "Logic in Computer Science '88", Edinburgh, IEEE Computer Society
    Press, 1988.

--
Y V Srinivas
Dept of ICS, University of California, Irvine, CA 92717