Enable syntax highlighting

DevGuide.md

@@ -24,13 +24,17 @@ Parser warnings come in two flavors: problems and notes.
 
 Notes are only emitted when parsing succeeds (they are stored in the Parsec user state). For example, a note is emitted when adding spaces around `=` in assignments, because if the parser later fails (i.e. it's not actually an assignment), we want to discard the suggestion:
 
+```haskell
 when (hasLeftSpace || hasRightSpace) $
     parseNoteAt pos ErrorC 1068 "Don't put spaces around the = in assignments."
+```
 
 On the other hand, problems are always emitted, even when parsing fails (they are stored in a StateT higher than Parsec in the transformer stack). For example, a problem is emitted for unicode quotes, because this issue is likely to cause parsing to fail:
 
+```haskell
 when (single && '\n' `elem` space) $
     parseProblemAt pos ErrorC 1080 "When breaking lines in [ ], you need \\ before the linefeed."
+```
 
 So basically, notes are emitted for non-fatal warnings while problems are emitted for fatal ones. 
 
@@ -50,17 +54,21 @@ AST analysis comes in two primary flavors: checks that run on the root node (som
 
 Here's a simple check designed to run on each node, using pattern matching to find backticks:
 
+```haskell
 checkBackticks _ (T_Backticked id list) | not (null list) =
     style id 2006 "Use $(..) instead of legacy `..`."
 checkBackticks _ _ = return ()
+````
 
 A lot of checks are just like this, though usually with a bit more matching logic.
 
 Each check is preceded by some mostly self-explanatory unit tests:
 
+```haskell
 prop_checkBackticks1 = verify checkBackticks "echo `foo`"
 prop_checkBackticks2 = verifyNot checkBackticks "echo $(foo)"
 prop_checkBackticks3 = verifyNot checkBackticks "echo `#inlined comment` foo"
+```
 
 There are a few specialized test types for efficiency reasons.
 
@@ -95,7 +103,7 @@ Ok, modules loaded: ShellCheck.Parser, ShellCheck.AST, ShellCheck.ASTLib, ShellC
 
 This has given us a REPL where we can call parsing functions. There's a convenient `debugParse` function that will take a parser and a string, and give the result. The main parser function is `readScript`:
 
-```
+```haskell
 *ShellCheck.Parser> debugParse readScript "sort file > tmp"
 Right (T_Annotation (Id 1) [] (T_Script (Id 0) "" [T_Pipeline (Id 3) [] [T_Redirecting (Id 4) [T_FdRedirect (Id 10) "" (T_IoFile (Id 11) (T_Greater (Id 12)) (T_NormalWord (Id 13) [T_Literal (Id 14) "tmp"]))] (T_SimpleCommand (Id 5) [] [T_NormalWord (Id 6) [T_Literal (Id 7) "sort"],T_NormalWord (Id 8) [T_Literal (Id 9) "file"]])]]))
 *ShellCheck.Parser>
@@ -103,7 +111,7 @@ Right (T_Annotation (Id 1) [] (T_Script (Id 0) "" [T_Pipeline (Id 3) [] [T_Redir
 
 Not very pretty, but we can see the part we're interested in:
 
-```
+```haskell
 (T_IoFile (Id 11) (T_Greater (Id 12)) (T_NormalWord (Id 13) [T_Literal (Id 14) "tmp"]))
 ```
 
@@ -114,7 +122,7 @@ We can compare this with the definition in `AST.hs`:
                         ^-- Filename (T_NormalWord)
 
 Let's just add a check to `Analytics.hs`:
-```
+```haskell
   checkTmpFilename _ token =
       case token of
         T_IoFile id operator filename  ->
@@ -124,7 +132,7 @@ Let's just add a check to `Analytics.hs`:
 
 and then append `checkTmpFilename` to the list of node checks at the top of the file:
 
-```
+```haskell
   nodeChecks :: [Parameters -> Token -> Writer [TokenComment] ()]
   nodeChecks = [
       checkUuoc
@@ -155,7 +163,7 @@ sort file > tmp
 Now we can flesh out the check. See `ASTLib.hs` and `AnalyzerLib.hs` for convenient functions to work with AST nodes, such as getting the name of an invoked command, getting a list of flags using canonical flag parsing rules, or in this case, getting the literal string of a T_NormalWord so that it doesn't matter if we use `> 'tmp'`, `> "tmp"` or `> "t"'m'p`:
 
 
-```
+```haskell
   checkTmpFilename _ token =
       case token of
         T_IoFile id operator filename  ->
@@ -166,7 +174,7 @@ Now we can flesh out the check. See `ASTLib.hs` and `AnalyzerLib.hs` for conveni
 
 We can also prepend a few unit tests that will automatically be picked up if they start with `prop_`:
 
-```
+```haskell
 prop_checkTmpFilename1 = verify checkTmpFilename "sort file > tmp"
 prop_checkTmpFilename2 = verifyNot checkTmpFilename "sort file > $tmp"
 ```