Add config get and dump commands.

doc/GUIDE_advanced.md

@@ -78,36 +78,52 @@ the command, see the [build command](build_command.md) documentation.
 
 ## The `stack config` commands
 
-The `stack config` commands provide assistence with accessing or modifying
+The `stack config` commands provide assistance with accessing or modifying
 Stack's configuration. See `stack config` for the available commands.
 
-## The `stack config env` command
+## The `stack config dump-*` commands
 
-`stack config env` outputs a script that sets or unsets environment variables
-for a Stack environment. Flags modify the script that is output:
+These commands dump YAML but can dump JSON with an added `--json` flag.
 
-* `--[no-]locals` (enabled by default) include/exclude local package information
-* `--[no-]ghc-package-path` (enabled by default) set `GHC_PACKAGE_PATH`
-  environment variable or not
-* `--[no-]stack-exe` (enabled by default) set `STACK_EXE` environment variable
-  or not
-* `--[no-]locale-utf8` (disabled by default) set the `GHC_CHARENC`
-  environment variable to `UTF-8` or not
-* `--[no-]keep-ghc-rts` (disabled by default) keep/discard any `GHCRTS`
-  environment variable
+## The `stack config dump-project` command
+
+The `stack config dump-project` command dumps project-only configuration. Any
+non-project configuration in the project is removed.
+
+## The `stack config dump-stack` command
+
+The `stack config dump-stack` command dumps configuration related to the
+operation of stack itself. This is non-project configuration. With `--lens` we
+can look at the configuration coming from the global settings, from stack
+settings within the project or the effective combination from those two
+locations.
+
+## The `stack config get` commands
+
+The `stack config get` commands gets values of keys in YAML configuration
+files but only those that can also be set.
+
+## The `stack config get resolver` command
+
+Gets the effective resolver.
+
+## The `stack config get *-ghc` commands
+
+The `--global` option will get these settings' global value.
+
+## The `stack config get system-ghc` commands
+
+Gets whether stack should use the system GHC installation.
+
+## The `stack config get install-ghc` command
+
+Gets whether stack should install GHC by itself.
 
 ## The `stack config set` commands
 
 The `stack config set` commands allow the values of keys in YAML configuration
 files to be set. See `stack config set` for the available keys.
 
-## The `stack config set install-ghc` command
-
-`stack config set install-ghc true` or `false` sets the `install-ghc` key in a
-YAML configuration file, accordingly. By default, the project-level
-configuration file (`stack.yaml`) is altered. The `--global` flag specifies the
-user-specific global configuration file (`config.yaml`).
-
 ## The `stack config set resolver` command
 
 `stack config set resolver <snapshot>` sets the `resolver` key in the
@@ -128,6 +144,28 @@ YAML configuration file, accordingly. By default, the project-level
 configuration file (`stack.yaml`) is altered. The `--global` flag specifies the
 user-specific global configuration file (`config.yaml`).
 
+## The `stack config set install-ghc` command
+
+`stack config set install-ghc true` or `false` sets the `install-ghc` key in a
+YAML configuration file, accordingly. By default, the project-level
+configuration file (`stack.yaml`) is altered. The `--global` flag specifies the
+user-specific global configuration file (`config.yaml`).
+
+## The `stack config env` command
+
+`stack config env` outputs a script that sets or unsets environment variables
+for a Stack environment. Flags modify the script that is output:
+
+* `--[no-]locals` (enabled by default) include/exclude local package information
+* `--[no-]ghc-package-path` (enabled by default) set `GHC_PACKAGE_PATH`
+  environment variable or not
+* `--[no-]stack-exe` (enabled by default) set `STACK_EXE` environment variable
+  or not
+* `--[no-]locale-utf8` (disabled by default) set the `GHC_CHARENC`
+  environment variable to `UTF-8` or not
+* `--[no-]keep-ghc-rts` (disabled by default) keep/discard any `GHCRTS`
+  environment variable
+
 ## The `stack dot` command
 
 If you'd like to get some insight into the dependency tree of your packages, you

package.yaml

@@ -52,6 +52,7 @@ dependencies:
 - base >= 4.16.3.0 && < 5
 - Cabal >= 3.6.3.0
 - aeson >= 2.0.3.0
+- aeson-pretty
 - annotated-wl-pprint
 - ansi-terminal
 - array