sumtype 1.2.8
A sum type with pattern matching
To use this package, run the following command in your project's root directory:
Manual usage
Put the following dependency into your project's dependences section:
sumtype
A sum type for modern D.
Note: Since DMD v2.097.0 (released 2021-06-03), sumtype
is part of the
standard library, and can be accessed by importing std.sumtype
.
Due to differing release schedules, features or bug fixes present in the latest
release of sumtype
may not be present in std.sumtype
. Please refer to the
official std.sumtype
documentation on dlang.org for information
about the standard-library version, and report any issues encountered while
using std.sumtype
on the official D issue tracker.
Features
- Pattern matching, including support for introspection-based matching.
- Self-referential types, using
This
. - Works with
pure
,@safe
,@nogc
,nothrow
, andimmutable
. - Compatible with
-betterC
and-dip1000
. - Zero runtime overhead compared to hand-written C.
- No heap allocation.
- Does not rely on runtime type information (
TypeInfo
).
Documentation
sumtype
uses adrdox to generate its documentation. To build your own
copy, run the following command from the root of the sumtype
repository:
path/to/adrdox/doc2 --genSearchIndex --genSource -o generated-docs src
Example
import std.math: isClose;
struct Fahrenheit { double degrees; }
struct Celsius { double degrees; }
struct Kelvin { double degrees; }
alias Temperature = SumType!(Fahrenheit, Celsius, Kelvin);
// Construct from any of the member types.
Temperature t1 = Fahrenheit(98.6);
Temperature t2 = Celsius(100);
Temperature t3 = Kelvin(273);
// Use pattern matching to access the value.
pure @safe @nogc nothrow
Fahrenheit toFahrenheit(Temperature t)
{
return Fahrenheit(
t.match!(
(Fahrenheit f) => f.degrees,
(Celsius c) => c.degrees * 9.0/5 + 32,
(Kelvin k) => k.degrees * 9.0/5 - 459.4
)
);
}
assert(toFahrenheit(t1).degrees.isClose(98.6));
assert(toFahrenheit(t2).degrees.isClose(212));
assert(toFahrenheit(t3).degrees.isClose(32));
// Use ref to modify the value in place.
pure @safe @nogc nothrow
void freeze(ref Temperature t)
{
t.match!(
(ref Fahrenheit f) => f.degrees = 32,
(ref Celsius c) => c.degrees = 0,
(ref Kelvin k) => k.degrees = 273
);
}
freeze(t1);
assert(toFahrenheit(t1).degrees.isClose(32));
// Use a catch-all handler to give a default result.
pure @safe @nogc nothrow
bool isFahrenheit(Temperature t)
{
return t.match!(
(Fahrenheit f) => true,
_ => false
);
}
assert(isFahrenheit(t1));
assert(!isFahrenheit(t2));
assert(!isFahrenheit(t3));
Installation
If you're using dub, add the sumtype package to your project as a dependency.
Alternatively, since it's a single, self-contained module, you can simply copy
sumtype.d
to your source directory and compile as usual.
- 1.2.8 released 7 months ago
- pbackus/sumtype
- BSL-1.0
- Copyright © 2018, Paul Backus
- Authors:
- Dependencies:
- none
- Versions:
-
1.2.8 2024-Mar-03 1.2.7 2022-Sep-05 1.2.6 2022-Jul-27 1.2.5 2022-Jun-21 1.2.4 2022-May-12 - Download Stats:
-
-
23 downloads today
-
211 downloads this week
-
628 downloads this month
-
165235 downloads total
-
- Score:
- 4.4
- Short URL:
- sumtype.dub.pm