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conditions
----------
Should conditions be bound to types, or have a certain scope?
type conditions:
int cond(value > 0) i = 1;
(float) sqrt(float cond(value >= 0));
() clear(list(T) postcond(value.length == 0));
typedef a = (
int cond(value > 0) x;
int y;
);
typedef a = (
int x;
int y;
) cond(x > y);
() create_list(count size, count capacity) cond(size <= capacity);
statement conditions (more/less flexible? more/less readable?):
int i = 1 cond(value > 0);
typedef a = (
int x;
int y;
) cond(x > y);
() create_list(count size, count capacity) cond(size <= capacity);
It's possible to use a value where a constrained type is expected in the
following cases (assuming the type is compatible, apart from it's conditions):
1) The target type has no conditions.
2) The target type has a weaker (or equally strict) condition as
the combined condition of the following:
a) the source type
b) the scope
c) other things that can the compiler can compute easily?
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