To make it simple: you are stressing the interpreter and not SPAD.
What I now say is a guess, but I am pretty confident that this is the
reason since...
(1) -> g(12)$Test(Float)
(1) 12.0
Type: Float
works as expected.
In order to figure out what you mean by "g 12", the interpreter must
look for a function that takes an integer. There is no such function.
Seemingly in your first case the interpreter is able to figure out that
there were a function g that is reasonably close.
It has to do two things. First, it must figure out how to package-call
g, i.e. it must find a reasonable parameter for "R: Ring". Integer will
do in this case. (I'm not at all sure whether the interpreter chooses
INT here, but it would be my first guess.)
Then it finds g: Float->Float so the interpreter has the convert 12 to
Float, before calling g. Since all that works, you are lucky in the
first case.
In the second case, you basically ask the interpreter to figure out a
domain that can be put in the argument of Test, i.e. fulfills the
category Algebra(Float). Seemingly, you simply ask too much from the
interpreter and thus it fails to find g.
Does that help?
Ralf
On 07/07/2011 05:57 PM, Yrogirg wrote:
I'm trying to understand the difference between the next two dummy
packages. The first one
)abbrev package TST Test
Test(R: Ring): with
g : Float -> Float
== add
g y == y
and it works as I expect:
(4) -> g 12
(4) 12.0
Type: Float
but a slightly different version
)abbrev package TST Test
Test(R: Algebra(Float)): with
g : Float -> Float
== add
g y == y
doesn't work:
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