Fetches a configuration value from a given key, if key is not found, you may pick the failure mode via the MonadThrow interface.

example:

>>> getConfigValue ["db", "user"] config :: Maybe Text
Just "root"
>>> getConfigValue ["db", "password"] config :: Maybe Text
Nothing

Fetches a configuration value from a given key, normally this key will point to a sub-config JSON object, which is then passed to the given JSON parser function. If key is not found, you may pick the failure mode via the MonadThrow interface.

example:

>>> import qualified Data.Aeson as JSON
>>> import qualified Data.Aeson.Types as JSON (Parser)

>>> connectInfoParser :: JSON.Value -> JSON.Parser DbConnectInfo

>>> getConfigValueWith connectInfoParser ["db"] config
Just (DbConnectInfo {...})

Parses a text input into a ConfigSpec, input can be JSON or YAML (if cabal flag is set).

Reads contents of a file and parses into a ConfigSpec, file contents can be either JSON or YAML (if cabal flag is set).

Gathers all default values from the etc/spec entries inside a ConfigSpec

Gathers configuration values from a list of files specified on the etc/filepaths entry of a Config Spec. This will return a Configuration Map with values from all filepaths merged in, and a list of errors in case there was an error reading one of the filepaths.

Gathers all OS Environment Variable values (env entries) from the etc/spec entries inside a ConfigSpec. This version of the function gathers the input from a list of tuples rather than the OS.

Gathers all OS Environment Variable values (env entries) from the etc/spec entries inside a ConfigSpec