My intention is to write two functions whose signatures differ only in
the type of the second argument.
I surely could use another function name, but I think it should also
work as I have coded it below. But I couln't make that work with SPAD.
While the Aldor compiler obviously produces code that seems to work, see
below.
======================================================================
)abbrev package FOO Foo
N ==> NonNegativeInteger
Z ==> Integer
Foo(R: Ring): with
foo: (R, N) -> R
if R has Field then foo: (R, Z) -> R
== add
import from N
foo(r: R, n: N): R == r^n
if R has Field then
foo(r: R, n: Z): R ==
n < 0 => inv foo(r, qcoerce(-n)@N)
foo(r, qcoerce(n)@N)
(1) -> foo(2,3)
(1) 8
Type:
PositiveInteger
(2) -> foo(2,-3)
Compiling function G732 with type Integer -> Boolean
C-c C-c
>> System error:
Interactive interrupt at #x100759B7E8.
I had to interrupt the function compilation. OK, without qualification,
I could live with it. But in a fresh FriCAS I then get
(1) -> foo(2, -3)$Foo(Fraction Integer)
and my CPU runs crazy. Looks like an endless loop.
Does that mean that SPAD forces me to choose two different names for the
two exported functions? That must be a bug.
Ralf
======================================================================
---------------- faa.as
#include "axiom"
N ==> NonNegativeInteger;
Z ==> Integer;
Faa(R: Ring): with {
faa: (R, N) -> R;
if R has Field then faa: (R, Z) -> R;
} == add {
import from N;
faa(r: R, n: N): R == r^n;
if R has Field then {
faa(r: R, n: Z): R == {
n < 0 => inv faa(r, qcoerce(-n)@N);
faa(r, qcoerce(n)@N);
}
}
}
-----------------------------------
(1) -> faa(2,3)
(1) 8
Type:
PositiveInteger
(2) -> faa(2,-3)
Compiling function G728 with type Integer -> Boolean
There are 1 exposed and 0 unexposed library operations named faa
having 2 argument(s) but none was determined to be applicable.
Use HyperDoc Browse, or issue
)display op faa
to learn more about the available operations. Perhaps
package-calling the operation or using coercions on the arguments
will allow you to apply the operation.
Cannot find a definition or applicable library operation named faa
with argument type(s)
PositiveInteger
Integer
Perhaps you should use "@" to indicate the required return type,
or "$" to specify which version of the function you need.
(2) -> faa(2,-3)$Faa(Fraction Integer)
1
(2) -
8
Type:
Fraction(Integer)
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