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 |
2024-04-25 16:44:54 UTC (04:23:59 hours 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 |
2024-04-25 16:42:01 UTC (04:26:52 hours ago) |
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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++ |
timestamp |
2024-04-25 16:41:44 UTC (04:27:09 hours 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 |
2024-04-25 16:38:50 UTC (04:30:03 hours 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 |
2024-04-25 16:38:35 UTC (04:30:18 hours ago) |
result |
success | log | rebuild |
toolchain |
public-0.16.0 |
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aarch64-linux-gnu |
tgt config |
linux_debian_12-clang_16 |
timestamp |
2024-04-25 16:34:49 UTC (04:34:04 hours ago) |
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public-0.16.0 |
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x86_64-apple-darwin22.5.0 |
tgt config |
macos_13-clang_15.0-static_O3 |
timestamp |
2024-04-25 03:13:00 UTC (17:55:53 hours 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 |
2024-04-25 03:12:18 UTC (17:56:35 hours ago) |
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success | log | rebuild |
toolchain |
public-0.16.0 |
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x86_64-apple-darwin22.5.0 |
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macos_13-clang_15.0 |
timestamp |
2024-04-25 03:11:41 UTC (17:57:12 hours 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 |
2024-04-24 20:17:13 UTC (01 00:51:40 days ago) |
result |
success | log | rebuild |
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public-0.16.0 |
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aarch64-linux-gnu |
tgt config |
linux_debian_12-gcc_13-static_O3 |
timestamp |
2024-04-24 13:03:06 UTC (01 08:05:47 days ago) |
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warning (update) | warning (test-installed) | log | rebuild |
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public-0.16.0 |
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aarch64-linux-gnu |
tgt config |
linux_debian_12-gcc_13-ndebug_O3 |
timestamp |
2024-04-24 13:00:38 UTC (01 08:08:15 days ago) |
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public-0.16.0 |
target |
aarch64-linux-gnu |
tgt config |
linux_debian_12-gcc_13-O3 |
timestamp |
2024-04-24 12:57:25 UTC (01 08:11:28 days ago) |
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warning (update) | warning (test-installed) | log | rebuild |
toolchain |
public-0.16.0 |
target |
aarch64-linux-gnu |
tgt config |
linux_debian_12-gcc_13 |
timestamp |
2024-04-24 12:51:17 UTC (01 08:17:36 days ago) |
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warning (update) | warning (test-installed) | log | rebuild |
toolchain |
public-0.16.0 |
target |
aarch64-linux-gnu |
tgt config |
linux_debian_12-clang_15_libc++ |
timestamp |
2024-04-24 09:40:38 UTC (01 11:28:15 days ago) |
result |
success | log | rebuild |
toolchain |
public-0.16.0 |
target |
aarch64-linux-gnu |
tgt config |
linux_debian_12-clang_15 |
timestamp |
2024-04-24 09:37:27 UTC (01 11:31:26 days ago) |
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public-0.16.0 |
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aarch64-linux-gnu |
tgt config |
linux_debian_11-gcc_12 |
timestamp |
2024-04-24 09:22:10 UTC (01 11:46:43 days ago) |
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public-0.16.0 |
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x86_64-linux-gnu |
tgt config |
linux_debian_12-gcc_12-bindist |
timestamp |
2024-04-24 08:26:43 UTC (01 12:42:09 days ago) |
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toolchain |
public-0.16.0 |
target |
x86_64-linux-gnu |
tgt config |
linux_debian_12-clang_16.0_libc++-O3 |
timestamp |
2024-04-24 06:18:52 UTC (01 14:50:01 days ago) |
result |
success | log | rebuild |
toolchain |
public-0.16.0 |
target |
x86_64-linux-gnu |
tgt config |
linux_debian_12-clang_16.0_libc++ |
timestamp |
2024-04-24 06:18:00 UTC (01 14:50:53 days ago) |
result |
success | log | rebuild |
toolchain |
public-0.16.0 |
target |
x86_64-linux-gnu |
tgt config |
linux_debian_12-clang_16.0_libc++-static_O3 |
timestamp |
2024-04-24 06:16:20 UTC (01 14:52:33 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 |
2024-04-24 06:14:57 UTC (01 14:53:56 days ago) |
result |
success | log | rebuild |
toolchain |
public-0.16.0 |
target |
x86_64-linux-gnu |
tgt config |
linux_debian_12-clang_16.0-static_O3 |
timestamp |
2024-04-24 06:13:43 UTC (01 14:55:10 days ago) |
result |
success | log | rebuild |
toolchain |
public-0.16.0 |
target |
x86_64-linux-gnu |
tgt config |
linux_debian_12-clang_16.0 |
timestamp |
2024-04-24 06:12:17 UTC (01 14:56:35 days ago) |
result |
success | log | rebuild |
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 |
timestamp |
2024-04-24 04:14:05 UTC (01 16:54:48 days ago) |
result |
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toolchain |
public-0.16.0 |
target |
x86_64-microsoft-win32-msvc14.3 |
tgt config |
windows_10-clang_16.0_llvm_msvc_17.6-O2 |
timestamp |
2024-04-24 04:09:09 UTC (01 16:59:44 days ago) |
result |
success | log | rebuild |
toolchain |
public-0.16.0 |
target |
x86_64-microsoft-win32-msvc14.3 |
tgt config |
windows_10-clang_16.0_llvm_msvc_17.6-static_O2 |
timestamp |
2024-04-24 04:08:37 UTC (01 17:00:16 days ago) |
result |
success | log | rebuild |
toolchain |
public-0.16.0 |
target |
x86_64-microsoft-win32-msvc14.3 |
tgt config |
windows_10-msvc_17.6 |
timestamp |
2024-04-24 04:02:43 UTC (01 17:06:10 days ago) |
result |
success | log | rebuild |
toolchain |
public-0.16.0 |
target |
x86_64-microsoft-win32-msvc14.3 |
tgt config |
windows_10-msvc_17.6-static_O2 |
timestamp |
2024-04-24 04:00:55 UTC (01 17:07:58 days ago) |
result |
success | log | rebuild |
toolchain |
public-0.16.0 |
target |
x86_64-microsoft-win32-msvc14.3 |
tgt config |
windows_10-msvc_17.6-O2 |
timestamp |
2024-04-24 04:00:29 UTC (01 17:08:24 days ago) |
result |
success | log | rebuild |
toolchain |
public-0.16.0 |
target |
x86_64-w64-mingw32 |
tgt config |
windows_10-gcc_12.2_mingw_w64-static_O2 |
timestamp |
2024-04-24 03:25:52 UTC (01 17:43:01 days ago) |
result |
success | log | rebuild |
toolchain |
public-0.16.0 |
target |
x86_64-w64-mingw32 |
tgt config |
windows_10-gcc_12.2_mingw_w64-O2 |
timestamp |
2024-04-24 03:25:04 UTC (01 17:43:49 days ago) |
result |
success | log | rebuild |
toolchain |
public-0.16.0 |
target |
x86_64-w64-mingw32 |
tgt config |
windows_10-gcc_12.2_mingw_w64 |
timestamp |
2024-04-24 03:20:20 UTC (01 17:48:33 days ago) |
result |
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toolchain |
public-0.16.0 |
target |
x86_64-microsoft-win32-msvc14.3 |
tgt config |
windows_10-msvc_17.5 |
timestamp |
2024-04-24 02:57:15 UTC (01 18:11:38 days ago) |
result |
success | log | rebuild |
toolchain |
public-0.16.0 |
target |
x86_64-microsoft-win32-msvc14.3 |
tgt config |
windows_10-clang_15.0_msvc_msvc_17.6 |
timestamp |
2024-04-24 02:56:15 UTC (01 18:12:38 days ago) |
result |
success | log | rebuild |
toolchain |
public-0.16.0 |
target |
x86_64-freebsd13.2 |
tgt config |
freebsd_13-clang_14.0-static_O3 |
timestamp |
2024-04-24 02:35:46 UTC (01 18:33:07 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 |
2024-04-24 02:33:38 UTC (01 18:35:15 days ago) |
result |
success | log | rebuild |
toolchain |
public-0.16.0 |
target |
x86_64-freebsd13.2 |
tgt config |
freebsd_13-clang_14.0 |
timestamp |
2024-04-24 02:33:07 UTC (01 18:35:46 days ago) |
result |
success | log | rebuild |
toolchain |
public-0.16.0 |
target |
x86_64-freebsd12.4 |
tgt config |
freebsd_12-clang_13.0 |
timestamp |
2024-04-24 02:32:24 UTC (01 18:36:29 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 |
2024-04-24 02:29:33 UTC (01 18:39:20 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 |
2024-04-24 02:23:08 UTC (01 18:45:45 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 |
2024-04-24 02:17:35 UTC (01 18:51:18 days ago) |
result |
success | log | rebuild |
toolchain |
public-0.16.0 |
target |
x86_64-linux-gnu |
tgt config |
linux_fedora_38-gcc_13-bindist |
timestamp |
2024-04-24 01:58:26 UTC (01 19:10:27 days ago) |
result |
warning (update) | log | rebuild |
toolchain |
public-0.16.0 |
target |
x86_64-apple-darwin22.5.0 |
tgt config |
macos_13-clang_14.0-static_O3 |
timestamp |
2024-04-23 15:03:47 UTC (02 06:05:06 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 |
2024-04-23 15:03:09 UTC (02 06:05:44 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 |
2024-04-23 15:02:28 UTC (02 06:06:25 days ago) |
result |
success | log | rebuild |
toolchain |
public-0.16.0 |
target |
x86_64-linux-gnu |
tgt config |
linux_debian_12-gcc_13.1-ndebug_O3 |
timestamp |
2024-04-23 14:06:41 UTC (02 07:02:12 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-static_O3 |
timestamp |
2024-04-23 13:55:55 UTC (02 07:12:58 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 |
2024-04-23 13:52:03 UTC (02 07:16:50 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 |
2024-04-23 13:51:54 UTC (02 07:16:59 days ago) |
result |
warning (update) | warning (test-installed) | 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) |