On 04/02/2011 02:50 PM, Yrogirg wrote:
And what's wrong with this one:
)abbrev package MYEXP MyExp
MyExp(F: Ring): with
myexp: (F, PositiveInteger) -> F
== add
myexp(x, n) ==
a : PositiveInteger -> F
a i == x
a n
All types are given explicitly, the resulted function should be
myexp(x, n) = x for all n
Well, I am not 100% sure what happens here, but I guess the spad
compiler isn't able to bring your declaration a : PositiveInteger -> F
together with the following definition a i == x. And, actually, why
should it?
You have not given a type for i, so maybe you mean a function
a(i: String): F == x
Why should the compiler assume that in your definition a i == x the i
stands for a PositiveInteger?
You probably know that Spad allows you to define something like (*), see
below.
To make your code work, you would have to give the type of the argument.
But you can do without the signature declaration by giving explicit
types to the argument and the result type.
---rhxBEGIN myexp.spad
)abbrev package MYEXP MyExp
MyExp(F: Ring): with
myexp: (F, PositiveInteger) -> F
== add
myexp(x, n) ==
a(i: PositiveInteger): F == x
a n
---rhxEND myexp.spad
I seem to remember
http://groups.google.com/group/fricas-devel/msg/c6b9ac05fad9e74c?hl=en
that there was a problem with local function anyway.
According to Waldek, they should work in the compiler (and Waldek
probably knows best), but you might want think of it if you run into
troubles.
Ralf
(*)
=============================================================
)abbrev package MY My
My(F: Ring): with
a: String -> F
a: Integer -> F
== add
a(i: Integer):F == -i::F
a(i: String): F == 1
=============================================================
(1) -> F := Fraction Integer
(1) Fraction(Integer)
Type: Type
(2) -> H := My F
(2) My(Fraction(Integer))
Type: Type
(3) -> a 3
(3) - 3
Type: Integer
(4) -> a "x"
(4) 1
Type: PositiveInteger
BTW, don't get confused about the return types. The function a actually
returns something of type Fraction(Integer), but the interpreter tries
to turn this into a simpler type.
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