And now we have polymorphism..
///////
struct X[t] {
a:int;
b:double;
c:t;
fun f (x:int) => self.a + x + x;
fun g => self.a;
proc s (x:int) => self.a = x;
fun cc => self.c,self.c;
fun cx[u] (q:u) => self.c,q;
};
var x = X (1,2.0, "Hi");
println$ x.a, x.b, f x 42, g x;
println$ x.a, x.b, x.f 42, x.g;
&x.s 5;
println$ x.a, x.b, x.f 42, x.g;
println x.cc;
println$ x.cx 99.2;
///////
~/felix>flx --test=build/release --force st
(1, 2, 85, 1)
(1, 2, 85, 1)
(5, 2, 89, 5)
(Hi, Hi)
(Hi, 99.2)
////////////
Note that:
* the type of x is deduced from the constructor as X[string]
* the function cx is polymorphic in its own right, as well
as being applied to a polymorphic struct
* the last case would only work since I fixed deduction for multiple arguments!
Unfortunately:
var closure = x.cx[string, double];
Felix only allows you to elide trailing type variables during deduction.
Here, we know the type of the first type variable is string since cx is applied
to x. But we have to specify the type of the second variable "u" as double
since there's no argument at this point.
We'd rather leave out the first type variable's spec here since it is known
but we can't. This is a typical of Felix higher order functions: the types are
usually listed in the order they're needed for arguments, which is
the reverse order we actually need since arguments are partially
applied from left to right but type variables can only be dropped from
right to left.
Still .. it's a minor nit!
--
john skaller
skal...@users.sourceforge.net
http://felix-lang.org
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