A modern C++ metaprogramming library. It provides high level algorithms to manipulate heterogeneous sequences, allows writing type-level computations with a natural syntax, provides tools to introspect user-defined types and much more
Your standard library for metaprogramming
Overview
#include <boost/hana.hpp>
#include <cassert>
#include <string>
namespace hana = boost::hana;
using namespace hana::literals;
struct Fish { std::string name; };
struct Cat { std::string name; };
struct Dog { std::string name; };
int main() {
// Sequences capable of holding heterogeneous objects, and algorithms
// to manipulate them.
auto animals = hana::make_tuple(Fish{"Nemo"}, Cat{"Garfield"}, Dog{"Snoopy"});
auto names = hana::transform(animals, [](auto a) {
return a.name;
});
assert(hana::reverse(names) == hana::make_tuple("Snoopy", "Garfield", "Nemo"));
// No compile-time information is lost: even if `animals` can't be a
// constant expression because it contains strings, its length is constexpr.
static_assert(hana::length(animals) == 3u, "");
// Computations on types can be performed with the same syntax as that of
// normal C++. Believe it or not, everything is done at compile-time.
auto animal_types = hana::make_tuple(hana::type_c<Fish*>, hana::type_c<Cat&>, hana::type_c<Dog*>);
auto animal_ptrs = hana::filter(animal_types, [](auto a) {
return hana::traits::is_pointer(a);
});
static_assert(animal_ptrs == hana::make_tuple(hana::type_c<Fish*>, hana::type_c<Dog*>), "");
// And many other goodies to make your life easier, including:
// 1. Access to elements in a tuple with a sane syntax.
static_assert(animal_ptrs[0_c] == hana::type_c<Fish*>, "");
static_assert(animal_ptrs[1_c] == hana::type_c<Dog*>, "");
// 2. Unroll loops at compile-time without hassle.
std::string s;
hana::int_c<10>.times([&]{ s += "x"; });
// equivalent to s += "x"; s += "x"; ... s += "x";
// 3. Easily check whether an expression is valid.
// This is usually achieved with complex SFINAE-based tricks.
auto has_name = hana::is_valid([](auto&& x) -> decltype((void)x.name) { });
static_assert(has_name(animals[0_c]), "");
static_assert(!has_name(1), "");
}
Depends (5)
Builds
toolchain |
public-0.16.0 |
target |
aarch64-linux-gnu |
tgt config |
linux_debian_12-clang_16_libc++-static_O3 |
timestamp |
2024-04-30 01:03:28 UTC (01 10:55:18 days ago) |
result |
success | log | rebuild |
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public-0.16.0 |
target |
aarch64-linux-gnu |
tgt config |
linux_debian_12-clang_16_libc++ |
timestamp |
2024-04-30 01:02:47 UTC (01 10:55:59 days ago) |
result |
success | log | rebuild |
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public-0.16.0 |
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aarch64-linux-gnu |
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linux_debian_12-clang_16_libc++-O3 |
timestamp |
2024-04-30 01:02:13 UTC (01 10:56:33 days ago) |
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public-0.16.0 |
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aarch64-linux-gnu |
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linux_debian_12-clang_16-static_O3 |
timestamp |
2024-04-30 00:58:59 UTC (01 10:59:47 days ago) |
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public-0.16.0 |
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aarch64-linux-gnu |
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linux_debian_12-clang_16-O3 |
timestamp |
2024-04-30 00:58:18 UTC (01 11:00:28 days ago) |
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toolchain |
public-0.16.0 |
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aarch64-linux-gnu |
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linux_debian_12-clang_16 |
timestamp |
2024-04-30 00:54:32 UTC (01 11:04:14 days ago) |
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public-0.16.0 |
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x86_64-linux-gnu |
tgt config |
linux_fedora_37-gcc_12.2-bindist |
timestamp |
2024-04-29 23:38:09 UTC (01 12:20:37 days ago) |
result |
success | log | rebuild |
toolchain |
public-0.16.0 |
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x86_64-linux-gnu |
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linux_debian_12-clang_16.0_libc++-O3 |
timestamp |
2024-04-29 21:06:36 UTC (01 14:52:10 days ago) |
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toolchain |
public-0.16.0 |
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x86_64-linux-gnu |
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linux_debian_12-clang_16.0_libc++-static_O3 |
timestamp |
2024-04-29 21:06:02 UTC (01 14:52:44 days ago) |
result |
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toolchain |
public-0.16.0 |
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x86_64-linux-gnu |
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linux_debian_12-clang_16.0-static_O3 |
timestamp |
2024-04-29 21:05:14 UTC (01 14:53:32 days ago) |
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public-0.16.0 |
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x86_64-linux-gnu |
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linux_debian_12-clang_16.0_libc++ |
timestamp |
2024-04-29 21:03:45 UTC (01 14:55:01 days ago) |
result |
success | log | rebuild |
toolchain |
public-0.16.0 |
target |
x86_64-linux-gnu |
tgt config |
linux_debian_12-clang_16.0-O3 |
timestamp |
2024-04-29 21:02:55 UTC (01 14:55:51 days ago) |
result |
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toolchain |
public-0.16.0 |
target |
x86_64-linux-gnu |
tgt config |
linux_debian_12-clang_16.0 |
timestamp |
2024-04-29 21:02:21 UTC (01 14:56:25 days ago) |
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toolchain |
public-0.16.0 |
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x86_64-microsoft-win32-msvc14.3 |
tgt config |
windows_10-clang_16.0_llvm_msvc_17.6-static_O2 |
timestamp |
2024-04-29 20:24:32 UTC (01 15:34:14 days ago) |
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public-0.16.0 |
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x86_64-microsoft-win32-msvc14.3 |
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windows_10-clang_16.0_llvm_msvc_17.6 |
timestamp |
2024-04-29 20:15:18 UTC (01 15:43:29 days ago) |
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public-0.16.0 |
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x86_64-microsoft-win32-msvc14.3 |
tgt config |
windows_10-clang_16.0_llvm_msvc_17.6-O2 |
timestamp |
2024-04-29 20:08:06 UTC (01 15:50:41 days ago) |
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public-0.16.0 |
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aarch64-linux-gnu |
tgt config |
linux_debian_12-clang_15_libc++ |
timestamp |
2024-04-29 19:24:07 UTC (01 16:34:39 days ago) |
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public-0.16.0 |
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aarch64-linux-gnu |
tgt config |
linux_debian_12-clang_15 |
timestamp |
2024-04-29 19:21:33 UTC (01 16:37:13 days ago) |
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toolchain |
public-0.16.0 |
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x86_64-w64-mingw32 |
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windows_10-gcc_12.2_mingw_w64 |
timestamp |
2024-04-29 18:42:15 UTC (01 17:16:31 days ago) |
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public-0.16.0 |
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x86_64-w64-mingw32 |
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windows_10-gcc_12.2_mingw_w64-static_O2 |
timestamp |
2024-04-29 18:37:56 UTC (01 17:20:50 days ago) |
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toolchain |
public-0.16.0 |
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x86_64-w64-mingw32 |
tgt config |
windows_10-gcc_12.2_mingw_w64-O2 |
timestamp |
2024-04-29 18:33:42 UTC (01 17:25:04 days ago) |
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public-0.16.0 |
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x86_64-microsoft-win32-msvc14.3 |
tgt config |
windows_10-msvc_17.6-static_O2 |
timestamp |
2024-04-29 13:45:47 UTC (01 22:12:59 days ago) |
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toolchain |
public-0.16.0 |
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x86_64-microsoft-win32-msvc14.3 |
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windows_10-msvc_17.6-O2 |
timestamp |
2024-04-29 13:44:28 UTC (01 22:14:18 days ago) |
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toolchain |
public-0.16.0 |
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x86_64-microsoft-win32-msvc14.3 |
tgt config |
windows_10-msvc_17.6 |
timestamp |
2024-04-29 13:42:41 UTC (01 22:16:05 days ago) |
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toolchain |
public-0.16.0 |
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x86_64-microsoft-win32-msvc14.3 |
tgt config |
windows_10-clang_15.0_msvc_msvc_17.6 |
timestamp |
2024-04-29 13:34:17 UTC (01 22:24:29 days ago) |
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toolchain |
public-0.16.0 |
target |
x86_64-microsoft-win32-msvc14.3 |
tgt config |
windows_10-msvc_17.5 |
timestamp |
2024-04-29 13:32:27 UTC (01 22:26:19 days ago) |
result |
success | log | rebuild |
toolchain |
public-0.16.0 |
target |
x86_64-linux-gnu |
tgt config |
linux_debian_12-gcc_12-bindist |
timestamp |
2024-04-29 13:31:17 UTC (01 22:27:29 days ago) |
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toolchain |
public-0.16.0 |
target |
x86_64-freebsd13.2 |
tgt config |
freebsd_13-clang_14.0-static_O3 |
timestamp |
2024-04-29 13:29:45 UTC (01 22:29:01 days ago) |
result |
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toolchain |
public-0.16.0 |
target |
x86_64-freebsd13.2 |
tgt config |
freebsd_13-clang_14.0 |
timestamp |
2024-04-29 13:27:44 UTC (01 22:31:02 days ago) |
result |
success | log | rebuild |
toolchain |
public-0.16.0 |
target |
x86_64-freebsd13.2 |
tgt config |
freebsd_13-clang_14.0-O3 |
timestamp |
2024-04-29 13:26:56 UTC (01 22:31:50 days ago) |
result |
success | log | rebuild |
toolchain |
public-0.16.0 |
target |
x86_64-freebsd12.4 |
tgt config |
freebsd_12-clang_13.0 |
timestamp |
2024-04-29 13:23:44 UTC (01 22:35:02 days ago) |
result |
success | log | rebuild |
toolchain |
public-0.16.0 |
target |
x86_64-linux-gnu |
tgt config |
linux_debian_12-clang_15.0_libc++ |
timestamp |
2024-04-29 13:23:28 UTC (01 22:35:18 days ago) |
result |
success | log | rebuild |
toolchain |
public-0.16.0 |
target |
x86_64-linux-gnu |
tgt config |
linux_debian_12-clang_15.0 |
timestamp |
2024-04-29 13:22:30 UTC (01 22:36:17 days ago) |
result |
success | log | rebuild |
toolchain |
public-0.16.0 |
target |
x86_64-linux-gnu |
tgt config |
linux_debian_11-gcc_12.1 |
timestamp |
2024-04-29 13:21:03 UTC (01 22:37:43 days ago) |
result |
success | log | rebuild |
toolchain |
public-0.16.0 |
target |
aarch64-linux-gnu |
tgt config |
linux_debian_11-gcc_12 |
timestamp |
2024-04-29 13:19:58 UTC (01 22:38:48 days ago) |
result |
success | log | rebuild |
toolchain |
public-0.16.0 |
target |
aarch64-linux-gnu |
tgt config |
linux_debian_12-gcc_13-ndebug_O3 |
timestamp |
2024-04-29 12:40:54 UTC (01 23:17:52 days ago) |
result |
warning (update) | warning (test-installed) | log | rebuild |
toolchain |
public-0.16.0 |
target |
aarch64-linux-gnu |
tgt config |
linux_debian_12-gcc_13-static_O3 |
timestamp |
2024-04-29 12:39:47 UTC (01 23:18:59 days ago) |
result |
warning (update) | warning (test-installed) | log | rebuild |
toolchain |
public-0.16.0 |
target |
aarch64-linux-gnu |
tgt config |
linux_debian_12-gcc_13 |
timestamp |
2024-04-29 12:38:55 UTC (01 23:19:51 days ago) |
result |
warning (update) | warning (test-installed) | log | rebuild |
toolchain |
public-0.16.0 |
target |
aarch64-linux-gnu |
tgt config |
linux_debian_12-gcc_13-O3 |
timestamp |
2024-04-29 12:38:36 UTC (01 23:20:10 days ago) |
result |
warning (update) | warning (test-installed) | log | rebuild |
toolchain |
public-0.16.0 |
target |
x86_64-linux-gnu |
tgt config |
linux_fedora_38-gcc_13-bindist |
timestamp |
2024-04-29 11:54:27 UTC (02 00:04:19 days ago) |
result |
warning (update) | log | rebuild |
toolchain |
public-0.16.0 |
target |
x86_64-linux-gnu |
tgt config |
linux_debian_12-gcc_13.1-static_O3 |
timestamp |
2024-04-29 11:28:22 UTC (02 00:30:24 days ago) |
result |
warning (update) | warning (test-installed) | log | rebuild |
toolchain |
public-0.16.0 |
target |
x86_64-linux-gnu |
tgt config |
linux_debian_12-gcc_13.1-O3 |
timestamp |
2024-04-29 11:27:58 UTC (02 00:30:48 days ago) |
result |
warning (update) | warning (test-installed) | log | rebuild |
toolchain |
public-0.16.0 |
target |
x86_64-linux-gnu |
tgt config |
linux_debian_12-gcc_13.1-ndebug_O3 |
timestamp |
2024-04-29 11:27:25 UTC (02 00:31:21 days ago) |
result |
warning (update) | warning (test-installed) | log | rebuild |
toolchain |
public-0.16.0 |
target |
x86_64-linux-gnu |
tgt config |
linux_debian_12-gcc_13.1 |
timestamp |
2024-04-29 11:26:07 UTC (02 00:32:39 days ago) |
result |
warning (update) | warning (test-installed) | log | rebuild |
toolchain |
public-0.16.0 |
target |
x86_64-apple-darwin22.5.0 |
tgt config |
macos_13-clang_14.0-static_O3 |
timestamp |
2024-04-28 22:04:37 UTC (02 13:54:09 days ago) |
result |
success | log | rebuild |
toolchain |
public-0.16.0 |
target |
x86_64-apple-darwin22.5.0 |
tgt config |
macos_13-clang_14.0-O3 |
timestamp |
2024-04-28 22:03:58 UTC (02 13:54:48 days ago) |
result |
success | log | rebuild |
toolchain |
public-0.16.0 |
target |
x86_64-apple-darwin22.5.0 |
tgt config |
macos_13-clang_14.0 |
timestamp |
2024-04-28 22:03:21 UTC (02 13:55:25 days ago) |
result |
success | log | rebuild |
toolchain |
public-0.16.0 |
target |
x86_64-apple-darwin22.5.0 |
tgt config |
macos_13-clang_15.0-static_O3 |
timestamp |
2024-04-28 16:30:55 UTC (02 19:27:52 days ago) |
result |
success | log | rebuild |
toolchain |
public-0.16.0 |
target |
x86_64-apple-darwin22.5.0 |
tgt config |
macos_13-clang_15.0-O3 |
timestamp |
2024-04-28 16:28:23 UTC (02 19:30:23 days ago) |
result |
success | log | rebuild |
toolchain |
public-0.16.0 |
target |
x86_64-apple-darwin22.5.0 |
tgt config |
macos_13-clang_15.0 |
timestamp |
2024-04-28 16:25:45 UTC (02 19:33:01 days ago) |
result |
success | log | rebuild |
target |
x86_64-apple-darwin22.5.0 |
tgt config |
macos_13-gcc_13_homebrew |
result |
excluded (https://github) |
target |
x86_64-apple-darwin22.5.0 |
tgt config |
macos_13-gcc_13_homebrew-O3 |
result |
excluded (https://github) |
target |
x86_64-apple-darwin22.5.0 |
tgt config |
macos_13-gcc_13_homebrew-static_O3 |
result |
excluded (https://github) |