On Tuesday, 27 October 2015 at 17:48:04 UTC, Meta wrote:
On Tuesday, 27 October 2015 at 15:06:07 UTC, TheFlyingFiddle
wrote:
This can arguably already be done cleaner in D.
if (auto worldFile = getAFile("world.json"))
{
auto world = parseJSON(worldFile);
if (auto mapFile = getAFile(world["map"))
{
//...
}
else enforce(false, "Failed to load: " ~ world["map"]);
}
else enforce(false, "Failed to load: world.json");
Or even:
auto worldFile = enforce(getAFile("world.json"), "Failed to
load: world.json");
auto world = parseJSON(worldFile);
auto mapFile = enforce(getAFile(world["map"]), "Failed to load:
" ~ world["map"]);
//...
From what I've seen in the Rust community, they try to avoid
using match as it's very syntactically heavy. They have all
kinds of idioms to avoid doing matches on Option, such as the
try! macro, unwrap_or, unwrap_or_else, etc.
That being said, pattern matching has been one of my
most-wanted D features for years.
Yes this is much cleaner. But it does not really force a user to
consider the empty case.
I mean this would still compile.
auto worldFile = getAFile("world.json");
auto world = parseJSON(worldFile);
auto mapFile = getAFile(world["map"]);
auto map = parseJSON(mapFile);
What I was after was a way to at compile time ensure that all
accesses to the value in the optional type are considered. From
my uses of Maybe in haskell i know this get's annoying quick so I
dunno if it's a good thing. But atleast you would know that in
all places that optionals are accessed a handler for the empty
case would be present.
