Generate README from niv

Main.hs

@@ -70,6 +70,7 @@ getVersionsSpec = do
       Just _ -> abortVersionsIsntAMap
       Nothing -> abortVersionsIsntJSON
 
+-- TODO: pretty
 setVersionsSpec :: VersionsSpec -> IO ()
 setVersionsSpec versionsSpec = encodeFile pathNixVersionsJson versionsSpec
 

README.md

@@ -31,9 +31,10 @@ Available commands:
   init                     Initialize a Nix project. Existing files won't be
                            modified.
   add                      Add dependency
-  show
+  show                     
   update                   Update dependencies
   drop                     Drop dependency
+
 ```
 
 
@@ -47,14 +48,15 @@ Examples:
   niv add my-package -v alpha-0.1 -t http://example.com/archive/<version>.zip
 
 Usage: niv add PACKAGE ([-b|--branch BRANCH] | [-o|--owner OWNER] |
-                         [-r|--repo REPO] | [-v|--version VERSION] |
-                         [-a|--attribute KEY=VAL] | [-t|--template URL])
-                         [-n|--name NAME]
+               [-r|--repo REPO] | [-v|--version VERSION] |
+               [-a|--attribute KEY=VAL] | [-t|--template URL]) [-n|--name NAME]
   Add dependency
 
 Available options:
-  -t,--template URL        foo
+  -t,--template URL        Used during 'update' when building URL. Occurrences
+                           of <foo> are replaced with attribute 'foo'.
   -h,--help                Show this help text
+
 ```
 
 
@@ -67,14 +69,16 @@ Examples:
   niv update nixpkgs
   niv update my-package -v beta-0.2
 
-Usage: niv update [PACKAGE] ([-b|--branch BRANCH] | [-o|--owner OWNER]
-                            | [-r|--repo REPO] | [-v|--version VERSION] |
-                            [-a|--attribute KEY=VAL] | [-t|--template URL])
+Usage: niv update [PACKAGE] ([-b|--branch BRANCH] | [-o|--owner OWNER] |
+                  [-r|--repo REPO] | [-v|--version VERSION] |
+                  [-a|--attribute KEY=VAL] | [-t|--template URL])
   Update dependencies
 
 Available options:
-  -t,--template URL        foo
+  -t,--template URL        Used during 'update' when building URL. Occurrences
+                           of <foo> are replaced with attribute 'foo'.
   -h,--help                Show this help text
+
 ```
 
 ### Drop
@@ -89,6 +93,7 @@ Usage: niv drop PACKAGE
 
 Available options:
   -h,--help                Show this help text
+
 ```
 
 [Nix]: https://nixos.org/nix/

README.tpl.md

@@ -0,0 +1,46 @@
+# niv
+
+A tool for dealing with third-party packages in [Nix].
+
+## Building
+
+Inside the provided nix shell:
+
+``` bash
+$ # GHCi:
+$ snack ghci
+$ # run:
+$ snack run -- <args>
+```
+
+## Usage
+
+* [Add](#add)
+* [Update](#update)
+* [Drop](#drop)
+
+```
+replace_niv_help
+```
+
+
+### Add
+
+```
+replace_niv_add_help
+```
+
+
+### Update
+
+```
+replace_niv_update_help
+```
+
+### Drop
+
+```
+replace_niv_drop_help
+```
+
+[Nix]: https://nixos.org/nix/

default.nix

@@ -1,2 +1,2 @@
 with { pkgs = import ./nix; };
-pkgs.niv
+{ inherit (pkgs) niv readme ; }

nix/overlay.nix

@@ -10,4 +10,39 @@
   (self: super:
     { niv = super.snack-lib.executable ../package.yaml ; }
   )
+
+  (self: super:
+    { readme = self.writeText "README.md"
+        (with
+          { template = builtins.readFile ../README.tpl.md;
+            niv_help = builtins.readFile
+              (self.runCommand "niv_help" { buildInputs = [ self.niv ]; }
+                "niv --help > $out"
+              );
+            niv_add_help = builtins.readFile
+              (self.runCommand "niv_add_help" { buildInputs = [ self.niv ]; }
+                "niv add --help > $out"
+              );
+            niv_update_help = builtins.readFile
+              (self.runCommand "niv_update_help" { buildInputs = [ self.niv ]; }
+                "niv update --help > $out"
+              );
+            niv_drop_help = builtins.readFile
+              (self.runCommand "niv_drop_help" { buildInputs = [ self.niv ]; }
+                "niv drop --help > $out"
+              );
+          };
+        self.lib.replaceStrings
+          [
+            "replace_niv_help"
+            "replace_niv_add_help"
+            "replace_niv_update_help"
+            "replace_niv_drop_help"
+          ]
+          [ niv_help niv_add_help niv_update_help niv_drop_help ]
+          template
+        );
+    }
+  )
+
 ]