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When I hit 999 exercises, I will finally have reached the ultimate state of soteriological release and no more exercises will be needed. The cycle will be complete. All that will be left is perfect quietude, freedom, and highest happiness.
51 lines
1.5 KiB
Zig
51 lines
1.5 KiB
Zig
//
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// Sometimes you know that a variable might hold a value or
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// it might not. Zig has a neat way of expressing this idea
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// called Optionals. An optional type just has a '?' like this:
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//
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// var foo: ?u32 = 10;
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//
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// Now foo can store a u32 integer OR null (a value storing
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// the cosmic horror of a value NOT EXISTING!)
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//
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// foo = null;
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//
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// if (foo == null) beginScreaming();
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//
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// Before we can use the optional value as the non-null type
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// (a u32 integer in this case), we need to guarantee that it
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// isn't null. One way to do this is to THREATEN IT with the
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// "orelse" statement.
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//
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// var bar = foo orelse 2;
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//
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// Here, bar will either equal the u32 integer value stored in
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// foo, or it will equal 2 if foo was null.
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//
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const std = @import("std");
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pub fn main() void {
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const result = deepThought();
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// Please threaten the result so that answer is either the
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// integer value from deepThought() OR the number 42:
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var answer: u8 = result;
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std.debug.print("The Ultimate Answer: {}.\n", .{answer});
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}
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fn deepThought() ?u8 {
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// It seems Deep Thought's output has declined in quality.
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// But we'll leave this as-is. Sorry Deep Thought.
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return null;
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}
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// Blast from the past:
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//
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// Optionals are a lot like error union types which can either
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// hold a value or an error. Likewise, the orelse statement is
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// like the catch statement used to "unwrap" a value or supply
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// a default value:
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//
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// var maybe_bad: Error!u32 = Error.Evil;
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// var number: u32 = maybe_bad catch 0;
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//
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