|Reference to "First-Class Data Type" firstname.lastname@example.org (1992-02-18)|
|re: First-class data types email@example.com (1992-03-05)|
|Re: First-class data types firstname.lastname@example.org (1992-03-05)|
|Re: First-class data types email@example.com (Raul Deluth Miller-Rockwell) (1992-03-06)|
|Re: First-class data types firstname.lastname@example.org (1992-03-06)|
|Re: First-class data types email@example.com (1992-03-05)|
|Re: First-class data types firstname.lastname@example.org (1992-03-09)|
|Re: First-class data types email@example.com (Norman P. Graham) (1992-03-11)|
|From:||Raul Deluth Miller-Rockwell <firstname.lastname@example.org>|
|Date:||Fri, 6 Mar 1992 05:53:20 GMT|
There is a nit to pick with the definition of 'first class
datatype' that asserts any operation can be applied to any object
of any first class datatype. Consider a language in which functions
Is that supposed to be a statement about the domain of every function
in the language? [e.g. that the empty function, which has no domain,
is not a proper member of the language?] If so that statement strikes
me as suspicious.
What is the XOR of two functions? What is the AND of two
let h = f XOR g where f and g are functions.
then h(x) is f(x) XOR g(x)
Similarly for AND.
What is the function-invocation of the integer constant 17? Of
the floating-point constant 0.5?
let h = the function 17
then h(x) is 17
Similarly for 0.5
Any language that admits arithmetic types and arithmetic operations
will have a hard time supporting first-class types. And of course,
once you subset the domain of datatypes and the operators that
apply in each sub-domain, the definition loses all generality.
This assertion may be true, but the above cases are easily resolvable.
[For people who aren't aware of this yet: both of the above features
are available, albeit with slightly different syntax, in the language
J. But so far J's just an interpreted language.]
Raul Deluth Miller-Rockwell <email@example.com>
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