From: Michael Orlitzky <michael@orlitzky.com>
Date: Tue, 7 Jul 2015 05:01:17 +0000 (-0400)
Subject: Move the Pretty class into its own module.
X-Git-Url: http://gitweb.michael.orlitzky.com/?p=dead%2Fharbl.git;a=commitdiff_plain;h=edb0055e306eb6b323bbc75bfb7d15089344af81;hp=e1060ef815f35309c7ca0800a345d7c54ce346bd

Move the Pretty class into its own module.
---

diff --git a/src/IPv4Pattern.hs b/src/IPv4Pattern.hs
index 0618453..70322d1 100644
--- a/src/IPv4Pattern.hs
+++ b/src/IPv4Pattern.hs
@@ -1,5 +1,3 @@
-{-# LANGUAGE FlexibleInstances #-}
-
 -- | An IPv4 address pattern has four fields separated by ".".  Each
 --   field is either a decimal number, or a sequence inside "[]" that
 --   contains one or more ";"-separated decimal numbers or
@@ -30,7 +28,6 @@ where
 import Test.Tasty ( TestTree, testGroup )
 import Test.Tasty.HUnit ( (@?=), testCase )
 import Text.Parsec (
-  ParseError,
   (<|>),
   char,
   digit,
@@ -42,25 +39,7 @@ import Text.Parsec (
 import Text.Parsec.String ( Parser )
 import Text.Read ( readMaybe )
 
-
-class Pretty a where
-  -- | Obtain a pretty 'String' representation of the given thingy.
-  prettyshow :: a -> String
-
-  -- | Pretty-print the given thingy.
-  pp :: a -> IO ()
-  pp = putStrLn . prettyshow
-
-
--- | Define a 'Pretty' instance for the result of 'parse'. This lets
---   us pretty-print the result of a parse attempt without worrying
---   about whether or not it failed. If the parse failed, you get the
---   same output that you usually would. Otherwise we pretty-print the
---   parsed value.
---
-instance Pretty a => Pretty (Either ParseError a) where
-  prettyshow (Left err) = show err
-  prettyshow (Right v)  = prettyshow v
+import Pretty
 
 
 -- * Octets
@@ -74,7 +53,7 @@ newtype IPv4Octet = IPv4Octet Int
 
 
 instance Pretty IPv4Octet where
-  prettyshow (IPv4Octet x) = show x
+  pretty_show (IPv4Octet x) = show x
 
 
 -- | Parse an IPv4 octet, which should contain a string of digits.
@@ -147,9 +126,9 @@ data IPv4SequenceMember =
 
 
 instance Pretty IPv4SequenceMember where
-  prettyshow (IPv4SequenceMemberOctet octet) = prettyshow octet
-  prettyshow (IPv4SequenceMemberOctetRange octet1 octet2) =
-    (prettyshow octet1) ++ ".." ++ (prettyshow octet2)
+  pretty_show (IPv4SequenceMemberOctet octet) = pretty_show octet
+  pretty_show (IPv4SequenceMemberOctetRange octet1 octet2) =
+    (pretty_show octet1) ++ ".." ++ (pretty_show octet2)
 
 
 -- | Parse an IPv4 \"sequence member\". A sequence member is either an
@@ -193,9 +172,9 @@ data IPv4Sequence =
 
 
 instance Pretty IPv4Sequence where
-  prettyshow (IPv4SequenceSingleMember member) = prettyshow member
-  prettyshow (IPv4SequenceOptions member subsequence) =
-    (prettyshow member) ++ ";" ++ (prettyshow subsequence)
+  pretty_show (IPv4SequenceSingleMember member) = pretty_show member
+  pretty_show (IPv4SequenceOptions member subsequence) =
+    (pretty_show member) ++ ";" ++ (pretty_show subsequence)
 
 
 -- | Parse an IPv4 \"sequence\". A sequence is whatever is allowed
@@ -212,14 +191,14 @@ instance Pretty IPv4Sequence where
 --   >>> parseTest v4sequence "1"
 --   IPv4SequenceSingleMember (IPv4SequenceMemberOctet (IPv4Octet 1))
 --
---   >>> pp $ parse v4sequence "" "1..2"
+--   >>> pretty_print $ parse v4sequence "" "1..2"
 --   1..2
 --
---   >>> pp $ parse v4sequence "" "1..2;8"
+--   >>> pretty_print $ parse v4sequence "" "1..2;8"
 --   1..2;8
 --
 v4sequence :: Parser IPv4Sequence
-v4sequence = try both <|> just_one -- Maybe sepBy is appropriate here?
+v4sequence = try both <|> just_one
   where
     both = do
       sm <- v4seq_member
@@ -238,8 +217,8 @@ data IPv4Field = IPv4FieldOctet IPv4Octet | IPv4FieldSequence IPv4Sequence
 
 
 instance Pretty IPv4Field where
-  prettyshow (IPv4FieldOctet octet) = prettyshow octet
-  prettyshow (IPv4FieldSequence s) = "[" ++ (prettyshow s) ++ "]"
+  pretty_show (IPv4FieldOctet octet) = pretty_show octet
+  pretty_show (IPv4FieldSequence s) = "[" ++ (pretty_show s) ++ "]"
 
 
 -- | Parse an IPv4 \"field\", which is either a boring old octet, or a
@@ -251,7 +230,7 @@ instance Pretty IPv4Field where
 --   >>> parseTest v4field "127"
 --   IPv4FieldOctet (IPv4Octet 127)
 --
---   >>> pp $ parse v4field "" "[127]"
+--   >>> pretty_print $ parse v4field "" "[127]"
 --   [127]
 --
 v4field :: Parser IPv4Field
@@ -275,13 +254,13 @@ data IPv4Pattern =
 
 
 instance Pretty IPv4Pattern where
-  prettyshow (IPv4Pattern f1 f2 f3 f4) =
-    (prettyshow f1) ++ "."
-                    ++ (prettyshow f2)
+  pretty_show (IPv4Pattern f1 f2 f3 f4) =
+    (pretty_show f1) ++ "."
+                    ++ (pretty_show f2)
                     ++ "."
-                    ++ (prettyshow f3)
+                    ++ (pretty_show f3)
                     ++ "."
-                    ++ (prettyshow f4)
+                    ++ (pretty_show f4)
 
 
 -- | Parse an ipv4 address pattern. This consists of four fields,
@@ -292,13 +271,13 @@ instance Pretty IPv4Pattern where
 --
 --   ==== _Examples_
 --
---   >>> pp $ parse v4pattern "" "127.0.0.1"
+--   >>> pretty_print $ parse v4pattern "" "127.0.0.1"
 --   127.0.0.1
 --
---   >>> pp $ parse v4pattern "" "127.0.[1..3].1"
+--   >>> pretty_print $ parse v4pattern "" "127.0.[1..3].1"
 --   127.0.[1..3].1
 --
---   >>> pp $ parse v4pattern "" "127.0.[1..3;8].1"
+--   >>> pretty_print $ parse v4pattern "" "127.0.[1..3;8].1"
 --   127.0.[1..3;8].1
 --
 --   In the module intro, it is mentioned that this is invalid:
@@ -312,7 +291,7 @@ instance Pretty IPv4Pattern where
 --   This one is /also/ invalid; however, we'll parse the valid part off
 --   the front of it:
 --
---   >>> pp $ parse v4pattern "" "1.2.3.3[6..9]"
+--   >>> pretty_print $ parse v4pattern "" "1.2.3.3[6..9]"
 --   1.2.3.3
 --
 v4pattern :: Parser IPv4Pattern
diff --git a/src/Pretty.hs b/src/Pretty.hs
new file mode 100644
index 0000000..360bd4c
--- /dev/null
+++ b/src/Pretty.hs
@@ -0,0 +1,33 @@
+{-# LANGUAGE FlexibleInstances #-}
+
+-- | A typeclass for pretty-printing. Types that wish to be
+--   pretty-printed should make themselves an instance of the 'Pretty'
+--   class. The only class function that they need to implement is
+--   'pretty_show', which turns the thing into a string in a nice
+--   way. The 'pretty_print' function then prints the result of
+--   'pretty_show' by default.
+--
+module Pretty
+where
+
+import Text.Parsec ( ParseError )
+
+
+class Pretty a where
+  -- | Obtain a pretty 'String' representation of the given thingy.
+  pretty_show :: a -> String
+
+  -- | Pretty-print the given thingy.
+  pretty_print :: a -> IO ()
+  pretty_print = putStrLn . pretty_show
+
+
+-- | Define a 'Pretty' instance for the result of 'parse'. This lets
+--   us pretty-print the result of a parse attempt without worrying
+--   about whether or not it failed. If the parse failed, you get the
+--   same output that you usually would. Otherwise we pretty-print the
+--   parsed value.
+--
+instance Pretty a => Pretty (Either ParseError a) where
+  pretty_show (Left err) = show err
+  pretty_show (Right v)  = pretty_show v