Added ConfigurableValue type class

* Added ConfigurableValue type class, for values that can be used in a
  config file, or to otherwise configure a program.
* The val function converts such values to String.

This was motivated by the bug caused by type Port = Int changing to
newtype Port = Port Int deriving Show
After that change, some things that used show port to generate config
files were broken. By using the ConfigurableValue type class instead,
such breakage can be prevented.

1 files changed, 36 insertions, 36 deletions

diff --git a/src/Propellor/Property/Parted.hs b/src/Propellor/Property/Parted.hs
index 40af3357..4d8924a5 100644
--- a/src/Propellor/Property/Parted.hs
+++ b/src/Propellor/Property/Parted.hs
@@ -30,14 +30,14 @@ import Data.Char
 import System.Posix.Files
 
 class PartedVal a where
-	val :: a -> String
+	pval :: a -> String
 
 -- | Types of partition tables supported by parted.
 data TableType = MSDOS | GPT | AIX | AMIGA | BSD | DVH | LOOP | MAC | PC98 | SUN
 	deriving (Show)
 
 instance PartedVal TableType where
-	val = map toLower . show
+	pval = map toLower . show
 
 -- | A disk's partition table.
 data PartTable = PartTable TableType [Partition]
@@ -82,9 +82,9 @@ data PartType = Primary | Logical | Extended
 	deriving (Show)
 
 instance PartedVal PartType where
-	val Primary = "primary"
-	val Logical = "logical"
-	val Extended = "extended"
+	pval Primary = "primary"
+	pval Logical = "logical"
+	pval Extended = "extended"
 
 -- | All partition sizing is done in megabytes, so that parted can
 -- automatically lay out the partitions.
@@ -94,7 +94,7 @@ newtype PartSize = MegaBytes Integer
 	deriving (Show)
 
 instance PartedVal PartSize where
-	val (MegaBytes n)
+	pval (MegaBytes n)
 		| n > 0 = show n ++ "MB"
 		-- parted can't make partitions smaller than 1MB;
 		-- avoid failure in edge cases
@@ -119,33 +119,33 @@ data PartFlag = BootFlag | RootFlag | SwapFlag | HiddenFlag | RaidFlag | LvmFlag
 	deriving (Show)
 
 instance PartedVal PartFlag where
-	val BootFlag = "boot"
-	val RootFlag = "root"
-	val SwapFlag = "swap"
-	val HiddenFlag = "hidden"
-	val RaidFlag = "raid"
-	val LvmFlag = "lvm"
-	val LbaFlag = "lba"
-	val LegacyBootFlag = "legacy_boot"
-	val IrstFlag = "irst"
-	val EspFlag = "esp"
-	val PaloFlag = "palo"
+	pval BootFlag = "boot"
+	pval RootFlag = "root"
+	pval SwapFlag = "swap"
+	pval HiddenFlag = "hidden"
+	pval RaidFlag = "raid"
+	pval LvmFlag = "lvm"
+	pval LbaFlag = "lba"
+	pval LegacyBootFlag = "legacy_boot"
+	pval IrstFlag = "irst"
+	pval EspFlag = "esp"
+	pval PaloFlag = "palo"
 
 instance PartedVal Bool where
-	val True = "on"
-	val False = "off"
+	pval True = "on"
+	pval False = "off"
 
 instance PartedVal Partition.Fs where
-	val Partition.EXT2 = "ext2"
-	val Partition.EXT3 = "ext3"
-	val Partition.EXT4 = "ext4"
-	val Partition.BTRFS = "btrfs"
-	val Partition.REISERFS = "reiserfs"
-	val Partition.XFS = "xfs"
-	val Partition.FAT = "fat"
-	val Partition.VFAT = "vfat"
-	val Partition.NTFS = "ntfs"
-	val Partition.LinuxSwap = "linux-swap"
+	pval Partition.EXT2 = "ext2"
+	pval Partition.EXT3 = "ext3"
+	pval Partition.EXT4 = "ext4"
+	pval Partition.BTRFS = "btrfs"
+	pval Partition.REISERFS = "reiserfs"
+	pval Partition.XFS = "xfs"
+	pval Partition.FAT = "fat"
+	pval Partition.VFAT = "vfat"
+	pval Partition.NTFS = "ntfs"
+	pval Partition.LinuxSwap = "linux-swap"
 
 data Eep = YesReallyDeleteDiskContents
 
@@ -168,19 +168,19 @@ partitioned eep disk (PartTable tabletype parts) = property' desc $ \w -> do
 	partedparams = concat $ mklabel : mkparts (1 :: Integer) mempty parts []
 	format (p, dev) = Partition.formatted' (partMkFsOpts p)
 		Partition.YesReallyFormatPartition (partFs p) dev
-	mklabel = ["mklabel", val tabletype]
+	mklabel = ["mklabel", pval tabletype]
 	mkflag partnum (f, b) =
 		[ "set"
 		, show partnum
-		, val f
-		, val b
+		, pval f
+		, pval b
 		]
 	mkpart partnum offset p =
 		[ "mkpart"
-		, val (partType p)
-		, val (partFs p)
-		, val offset
-		, val (offset <> partSize p)
+		, pval (partType p)
+		, pval (partFs p)
+		, pval offset
+		, pval (offset <> partSize p)
 		] ++ case partName p of
 			Just n -> ["name", show partnum, n]
 			Nothing -> []