为什么类型f（f b c）（f（f a b）（f a c））不匹配（。）？

时间：2018-08-25 16:44:50

标签： haskell types polymorphism function-composition hoogle

据我所知，我只是概括了APP_DEBUG=false的类型，但是，将其键入Hoogle时，没有得到任何结果。

我曾期望

[2018-08-25 12:22:04] production.ERROR: SQLSTATE[HY000] [2002] Connection refused {"exception":"[object] (PDOException(code: 2002): SQLSTATE[HY000] [2002] Connection refused at /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Database/Connectors/Connector.php:67)
[stacktrace]
#0 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Database/Connectors/Connector.php(67): PDO->__construct('mysql:host=127....', 'root', 'C4f2469dcF!', Array)
#1 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Database/Connectors/Connector.php(43): Illuminate\\Database\\Connectors\\Connector->createPdoConnection('mysql:host=127....', 'root', 'C4f2469dcF!', Array)
#2 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Database/Connectors/MySqlConnector.php(24): Illuminate\\Database\\Connectors\\Connector->createConnection('mysql:host=127....', Array, Array)
#3 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Database/Connectors/ConnectionFactory.php(183): Illuminate\\Database\\Connectors\\MySqlConnector->connect(Array)
#4 [internal function]: Illuminate\\Database\\Connectors\\ConnectionFactory->Illuminate\\Database\\Connectors\\{closure}()
#5 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Database/Connection.php(915): call_user_func(Object(Closure))
#6 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Database/Connection.php(940): Illuminate\\Database\\Connection->getPdo()
#7 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Database/Connection.php(399): Illuminate\\Database\\Connection->getReadPdo()
#8 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Database/Connection.php(325): Illuminate\\Database\\Connection->getPdoForSelect(true)
#9 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Database/Connection.php(657): Illuminate\\Database\\Connection->Illuminate\\Database\\{closure}('select * from `...', Array)
#10 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Database/Connection.php(624): Illuminate\\Database\\Connection->runQueryCallback('select * from `...', Array, Object(Closure))
#11 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Database/Connection.php(333): Illuminate\\Database\\Connection->run('select * from
`...', Array, Object(Closure))
#12 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Database/Query/Builder.php(1719): Illuminate\\Database\\Connection->select('select
* from `...', Array, true)
#13 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Database/Query/Builder.php(1704): Illuminate\\Database\\Query\\Builder->runSelect()
#14 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Database/Eloquent/Builder.php(483): Illuminate\\Database\\Query\\Builder->get(Array)
#15 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Database/Eloquent/Builder.php(467): Illuminate\\Database\\Eloquent\\Builder->getModels(Array)
#16 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Database/Eloquent/Model.php(360): Illuminate\\Database\\Eloquent\\Builder->get(Array)
#17 /var/app/html/releases/20180824022105/app/Category.php(13): Illuminate\\Database\\Eloquent\\Model::all()
#18 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Cache/Repository.php(327): App\\Category::App\\{closure}()
#19 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Cache/CacheManager.php(304): Illuminate\\Cache\\Repository->remember('list-categories', NULL, Object(Closure))
#20 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Support/Facades/Facade.php(221): Illuminate\\Cache\\CacheManager->__call('remember', Array)
#21 /var/app/html/releases/20180824022105/app/Category.php(20): Illuminate\\Support\\Facades\\Facade::__callStatic('remember', Array)
#22 /var/app/html/releases/20180824022105/routes/web.php(150): App\\Category::getCategories()
#23 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Routing/Router.php(389): Illuminate\\Routing\\Router->{closure}(Object(Illuminate\\Routing\\Router))
#24 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Routing/Router.php(349): Illuminate\\Routing\\Router->loadRoutes(Object(Closure))
#25 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Support/Facades/Facade.php(221): Illuminate\\Routing\\Router->group(Array, Object(Closure))
#26 /var/app/html/releases/20180824022105/routes/web.php(162): Illuminate\\Support\\Facades\\Facade::__callStatic('group', Array)
#27 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Routing/Router.php(393): require('/var/www/turico...')
#28 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Routing/Router.php(349): Illuminate\\Routing\\Router->loadRoutes('/var/www/turico...')
#29 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Routing/RouteRegistrar.php(105): Illuminate\\Routing\\Router->group(Array, '/var/www/turico...')
#30 /var/app/html/releases/20180824022105/app/Providers/RouteServiceProvider.php(56): Illuminate\\Routing\\RouteRegistrar->group('/var/www/turico...')
#31 /var/app/html/releases/20180824022105/app/Providers/RouteServiceProvider.php(40): App\\Providers\\RouteServiceProvider->mapWebRoutes()
#32 [internal function]: App\\Providers\\RouteServiceProvider->map()
#33 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Container/BoundMethod.php(29): call_user_func_array(Array, Array)
#34 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Container/BoundMethod.php(87): Illuminate\\Container\\BoundMethod::Illuminate\\Container\\{closure}()
#35 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Container/BoundMethod.php(31): Illuminate\\Container\\BoundMethod::callBoundMethod(Object(Illuminate\\Foundation\\Application), Array, Object(Closure))
#36 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Container/Container.php(549): Illuminate\\Container\\BoundMethod::call(Object(Illuminate\\Foundation\\Application), Array, Array, NULL)
#37 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Foundation/Support/Providers/RouteServiceProvider.php(74): Illuminate\\Container\\Container->call(Array)
#38 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Foundation/Support/Providers/RouteServiceProvider.php(33): Illuminate\\Foundation\\Support\\Providers\\RouteServiceProvider->loadRoutes()
#39 /var/app/html/releases/20180824022105/app/Providers/RouteServiceProvider.php(28): Illuminate\\Foundation\\Support\\Providers\\RouteServiceProvider->boot()
#40 [internal function]: App\\Providers\\RouteServiceProvider->boot()
#41 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Container/BoundMethod.php(29): call_user_func_array(Array, Array)
#42 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Container/BoundMethod.php(87): Illuminate\\Container\\BoundMethod::Illuminate\\Container\\{closure}()
#43 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Container/BoundMethod.php(31): Illuminate\\Container\\BoundMethod::callBoundMethod(Object(Illuminate\\Foundation\\Application), Array, Object(Closure))
#44 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Container/Container.php(549): Illuminate\\Container\\BoundMethod::call(Object(Illuminate\\Foundation\\Application), Array, Array, NULL)
#45 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Foundation/Application.php(792): Illuminate\\Container\\Container->call(Array)
#46 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Foundation/Application.php(775): Illuminate\\Foundation\\Application->bootProvider(Object(App\\Providers\\RouteServiceProvider))
#47 [internal function]: Illuminate\\Foundation\\Application->Illuminate\\Foundation\\{closure}(Object(App\\Providers\\RouteServiceProvider), 26)
#48 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Foundation/Application.php(776): array_walk(Array, Object(Closure))
#49 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Foundation/Bootstrap/BootProviders.php(17): Illuminate\\Foundation\\Application->boot()
#50 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Foundation/Application.php(213): Illuminate\\Foundation\\Bootstrap\\BootProviders->bootstrap(Object(Illuminate\\Foundation\\Application))
#51 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Foundation/Http/Kernel.php(162): Illuminate\\Foundation\\Application->bootstrapWith(Array)
#52 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Foundation/Http/Kernel.php(146): Illuminate\\Foundation\\Http\\Kernel->bootstrap()
#53 /var/app/html/releases/20180824022105/vendor/laravel/framework/src/Illuminate/Foundation/Http/Kernel.php(116): Illuminate\\Foundation\\Http\\Kernel->sendRequestThroughRouter(Object(Illuminate\\Http\\Request))
#54 /var/app/html/releases/20180824022105/public/index.php(55): Illuminate\\Foundation\\Http\\Kernel->handle(Object(Illuminate\\Http\\Request))
#55 {main}
"}

匹配

(.)

1 个答案:

答案 0 :(得分：3)

技术上的答案是，Hoogle将搜索分为(->)外部部分的参数和返回类型，然后在组合结果之前分别搜索每个部分。外部(->)受到非常特殊的对待，特别是很高兴对参数进行重新排序。

Hoogle这样工作的最根本原因是它是搜索引擎，而不是统一引擎。如果您正在搜索以上内容，然后返回(.)，那是否可以回答您的问题？我的猜测可能不是。我最喜欢的示例是搜索"a -> [(a,b)] -> b"时应返回lookup，即使它不是统一的。

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