Expressing range constraints in CNF form
Adam D. Ruppe via Digitalmars-d
digitalmars-d at puremagic.com
Sun Jun 11 17:13:46 PDT 2017
On Sunday, 11 June 2017 at 00:28:58 UTC, Andrei Alexandrescu
wrote:
> // Also possible (no change to the language)
> enum bool isInputRange(R) =
> is(typeof((ref R r) => r)) && msg("must be copyable")
Or how about
enum bool isInputRange(R) =
isCopyable!R &&
supportsBoolEmpty!R &&
supportsFront!R &&
supportsPopFront!R;
and the compiler just calls out which condition didn't match?
> && is(typeof(lvalueOf!R.popFront)) && msg("must support
> back");
hey look you already messed up the string by repeating it.
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