tools: start generating cabal files with hpack

hakyll-std's cabal file is now generated by hpack from an easier yaml
config file, which looks like a valuable timesaver. "make gencabalfiles"
will regenerate this cabal file (and soon the others) when needed.

Makefile

@@ -15,6 +15,7 @@
 # - shelltestrunner (latest version from hackage or possibly git), runs functional tests
 # - hasktags, generates tag files for code navigation
 # - profiteur, renders profiles as interactive html
+# - hpack, generates cabal files from package.yaml files
 # - hakyll-std, my generic site-building hakyll script
 #
 # Kinds of hledger builds:
@@ -112,7 +113,10 @@ SOURCEFILES:= \
 
 CABALFILES:= \
 	hledger/hledger.cabal \
-	hledger-*/*.cabal
+	hledger-*/*.cabal \
+
+CABALFILESFROMHPACK:= \
+	doc/site/hakyll-std.cabal
 
 WEBFILES:= \
 	hledger-web/templates/* \
@@ -820,9 +824,7 @@ $(call def-help-subsection,DOCUMENTATION:)
 doc/site/hakyll-std hakyll-std: \
 	doc/site/hakyll-std.hs \
 	doc/site/TableOfContents.hs \
-	doc/site/hakyll-std.cabal \
-	doc/site/stack.yaml \
-	$(call def-help,hakyll-std, build a generic hakyll site builder script )
+		$(call def-help,hakyll-std, build a generic hakyll site builder script )
 	cd doc/site; stack ghc hakyll-std
 
 site: doc/site/hakyll-std \
@@ -1275,13 +1277,34 @@ tagrelease: \
 ###############################################################################
 $(call def-help-subsection,MISCELLANEOUS:)
 
+# allow automatic variables in the prerequisites of subsequent rules
+.SECONDEXPANSION:
+
+gencabalfiles: $$(CABALFILESFROMHPACK) \
+		$(call def-help,gencabalfiles, regenerate cabal files from their package.yaml definitions )
+
+%.cabal: $$(dir $$@)package.yaml \
+		$(call def-help-hide,PATH/SOME.cabal, regenerate a cabal file from its package.yaml definition with hpack )
+	cd $(dir $*) && \
+	hpack && \
+	touch $(notdir $@) && \
+	cabal check
+
+cabal%: \
+	$(call def-help,cabalCMD, run cabal CMD inside each hledger package directory )
+	for p in $(PACKAGES); do (cd $$p; cabal $*); done
+
+all%: \
+	$(call def-help,all"CMD", run CMD inside each hledger package directory )
+	for p in $(PACKAGES); do (cd $$p; $*); done
+
 usage: cabalusage stackusage \
 	$(call def-help,usage, show size of various dirs )
 	du -sh .git bin data doc extra
 	du -sh .
 
 stackusage: \
-	$(call def-help,stackusage, show size of stack working dirs )
+	$(call def-help,stackusage, show size of stack working dirs if any )
 	-du -shc `find . -name '.stack*'`
 
 cabalusage: \
@@ -1322,14 +1345,6 @@ Clean: stackclean cabalclean cleanghc cleantags \
 
 # reverse = $(if $(wordlist 2,2,$(1)),$(call reverse,$(wordlist 2,$(words $(1)),$(1))) $(firstword $(1)),$(1))
 
-cabal%: \
-	$(call def-help,cabalCMD, run cabal CMD inside each hledger package directory )
-	for p in $(PACKAGES); do (cd $$p; cabal $*); done
-
-all%: \
-	$(call def-help,all"CMD", run CMD inside each hledger package directory )
-	for p in $(PACKAGES); do (cd $$p; $*); done
-
 ###############################################################################
 # LOCAL UNTRACKED CUSTOMISATIONS
 

doc/developer-guide.md

@@ -209,10 +209,10 @@ and the default view given by [bugs.hledger.org](http://bugs.hledger.org) exclud
     $ cd hledger
     ```
 
-3. Install optional extra tools (see the Makefile for a list):
+3. Install [GNU Make](http://www.gnu.org/software/make) and other optional extra tools (see the Makefile for a list):
 
     ```shell
-    $ stack install shelltestrunner hasktags profiteur
+    $ stack install shelltestrunner hasktags profiteur hpack
     ```
 
 4. Run `make` or `stack --help` to see some suggested commands:

doc/site/hakyll-std.cabal

@@ -1,39 +1,45 @@
-name:                hakyll-std
-version:             0.1.0
-synopsis:            Generic hakyll site builder script.
-description:         Generic hakyll site builder script.
-homepage:            http://github.com/simonmichael/hledger
-license:             BSD3
-license-file:        LICENSE
-author:              Simon Michael
-maintainer:          simon@joyful.com
--- copyright:           
-category:            Web
-build-type:          Simple
--- extra-source-files:  
-cabal-version:       >=1.10
+-- This file has been generated from package.yaml by hpack version 0.5.2.
+--
+-- see: https://github.com/sol/hpack
 
--- library
---   hs-source-dirs:      src
---   build-depends:       base >= 4.7 && < 5
---   default-language:    Haskell2010
+name:           hakyll-std
+version:        0.1.0
+synopsis:       Generic hakyll site builder script (shipped with hledger)
+description:    A simple hakyll website builder suitable for (eg) software-related websites, intended to be used as-is without recompilation. Features:
+                .
+                - renders markdown and common web file types found in standard places
+                - a site.tmpl template will be used when rendering markdown files
+                - "- toc" in markdown files is replaced by a table of contents
+                - fenced code blocks are appropriately syntax-highlighted by highlighting-kate
+                  (you should provide a syntax.css)
+                .
+                See the module doc (follow homepage link) for precise details.
+category:       Web
+homepage:       https://github.com/simonmichael/hledger/blob/master/doc/site/hakyll-std.hs
+bug-reports:    https://github.com/simonmichael/hledger/issues
+author:         Simon Michael
+maintainer:     -
+license:        BSD3
+license-file:   LICENSE
+build-type:     Simple
+cabal-version:  >= 1.10
+
+source-repository head
+  type: git
+  location: https://github.com/simonmichael/hledger
 
 executable hakyll-std
-  default-language:    Haskell2010
-  ghc-options:         -threaded -rtsopts -with-rtsopts=-N
-  hs-source-dirs:      .
-  main-is:             hakyll-std.hs
-  other-modules:       TableOfContents
-  build-depends:       base >= 4.7 && < 5
-                      ,hakyll >=4.7
-                      ,pandoc >=1.15
-                      ,pandoc-types
-                      ,process
-                      ,directory
-                      ,data-default
-                      ,blaze-html
-                      ,containers
-
--- source-repository head
---   type:     git
---   location: https://github.com/simonmichael/hledger
+  main-is: hakyll-std.hs
+  build-depends:
+      base >= 4.7 && < 5
+    , hakyll >=4.7
+    , pandoc
+    , pandoc-types
+    , process
+    , directory
+    , data-default
+    , blaze-html
+    , containers
+  other-modules:
+      TableOfContents
+  default-language: Haskell2010

doc/site/package.yaml

@@ -0,0 +1,39 @@
+# hpack specification for generating the cabal file
+# (run "hpack" in this directory)
+
+name        : hakyll-std
+version     : 0.1.0
+license     : BSD3
+synopsis    : Generic hakyll site builder script (shipped with hledger)
+description : |
+  A simple hakyll website builder suitable for (eg) software-related websites, intended to be used as-is without recompilation. Features:
+
+  - renders markdown and common web file types found in standard places
+  - a site.tmpl template will be used when rendering markdown files
+  - "- toc" in markdown files is replaced by a table of contents
+  - fenced code blocks are appropriately syntax-highlighted by highlighting-kate
+    (you should provide a syntax.css)
+
+  See the module doc (follow homepage link) for precise details.
+
+category    : Web
+github      : simonmichael/hledger
+homepage    : https://github.com/simonmichael/hledger/blob/master/doc/site/hakyll-std.hs
+author      : Simon Michael
+maintainer  : '-'
+
+dependencies:
+  - base >= 4.7 && < 5
+  - hakyll >=4.7
+  - pandoc #>=1.15
+  - pandoc-types
+  - process
+  - directory
+  - data-default
+  - blaze-html
+  - containers
+
+executables:
+  hakyll-std:
+    main: hakyll-std.hs
+    other-modules: TableOfContents