Hoogle Search

Within LTS Haskell 24.6 (ghc-9.10.2)

Note that Stackage only displays results for the latest LTS and Nightly snapshot. Learn more.

  1. type family Lookup (a1 :: a) (a2 :: [(a, b)]) :: Maybe b

    singletons-base Data.List.Singletons

    No documentation available.

  2. type family Lookup (a1 :: a) (a2 :: [(a, b)]) :: Maybe b

    singletons-base Prelude.Singletons

    No documentation available.

  3. class Lookup (f :: Type -> Type)

    keys Data.Key

    No documentation available.

  4. module Network.DNS.Lookup

    Simple, high-level DNS lookup functions for clients. All of the lookup functions necessary run in IO since they interact with the network. The return types are similar, but differ in what can be returned from a successful lookup. We can think of the return type as either "what I asked for" or "an error". For example, the lookupA function, if successful, will return a list of IPv4. The lookupMX function will instead return a list of (Domain,Int) pairs, where each pair represents a hostname and its associated priority. The order of multiple results may not be consistent between lookups. If you require consistent results, apply sort to the returned list. The errors that can occur are the same for all lookups. Namely:

    • Timeout
    • Wrong sequence number (foul play?)
    • Unexpected data in the response
    If an error occurs, you should be able to pattern match on the DNSError constructor to determine which of these is the case. Note: A result of "no records" is not considered an error. If you perform, say, an 'AAAA' lookup for a domain with no such records, the "success" result would be Right []. We perform a successful lookup of "www.example.com": 
    >>> let hostname = Data.ByteString.Char8.pack "www.example.com"

>>> 

>>> rs <- makeResolvSeed defaultResolvConf

>>> withResolver rs $ \resolver -> lookupA resolver hostname
Right [93.184.216.34]
    The only error that we can easily cause is a timeout. We do this by creating and utilizing a ResolvConf which has a timeout of one millisecond and a very limited number of retries: 
    >>> let hostname2 = Data.ByteString.Char8.pack "www.example.com"

>>> let badrc = defaultResolvConf { resolvTimeout = 0, resolvRetry = 1 }

>>> 

>>> rs2 <- makeResolvSeed badrc

>>> withResolver rs2 $ \resolver -> lookupA resolver hostname2
Left RetryLimitExceeded
    As is the convention, successful results will always be wrapped in a Right while errors will be wrapped in a Left. For convenience, you may wish to enable GHC's OverloadedStrings extension. This will allow you to avoid calling pack on each domain name. See https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/glasgow_exts.html#overloaded-string-literals for more information. In the following examples, we assuem this extension is enabled. All lookup functions eventually call lookupRaw. See its documentation to understand the concrete lookup behavior.

  5. module Language.Haskell.GHC.ExactPrint.Lookup

    No documentation available.

  6. type Lookup a = Either [Error] a

    liquidhaskell-boot Language.Haskell.Liquid.Bare.Resolve

    No documentation available.

  7. type family Lookup dim (lcsu :: LCSU Type)

    units Data.Metrology

    No documentation available.

  8. type family Lookup dim (lcsu :: LCSU Type)

    units Data.Metrology.Internal

    No documentation available.

  9. Lookup :: Exp -> MemberId -> Exp

    Agda Agda.Compiler.JS.Syntax

    No documentation available.

  10. module Data.PerfectHash.Lookup

    Note that what is referred to as a "nonce" in this library may be better known as a "salt".

Page 27 of many | Previous | Next