Add Idris.

This adds Idris into the mix and uses the text-only parser for now, pending
upstream merging this patch in:
https://bitbucket.org/birkenfeld/pygments-main/pull-request/210/idris-lexer-added-lexer-for-idris/diff

Once that gets merged in, the lexer should change to idris.

lib/linguist/languages.yml

@@ -628,6 +628,13 @@ INI:
   - .properties
   primary_extension: .ini
 
+Idris:
+  type: programming
+  lexer: Text only
+  primary_extension: .idr
+  extensions:
+  - .lidr
+
 Inno Setup:
   primary_extension: .iss
   lexer: Text only

samples/Idris/Chars.idr

@@ -0,0 +1,42 @@
+module Prelude.Char
+
+import Builtins
+
+isUpper : Char -> Bool
+isUpper x = x >= 'A' && x <= 'Z'
+
+isLower : Char -> Bool
+isLower x = x >= 'a' && x <= 'z'
+
+isAlpha : Char -> Bool
+isAlpha x = isUpper x || isLower x
+
+isDigit : Char -> Bool
+isDigit x = (x >= '0' && x <= '9')
+
+isAlphaNum : Char -> Bool
+isAlphaNum x = isDigit x || isAlpha x
+
+isSpace : Char -> Bool
+isSpace x = x == ' '  || x == '\t' || x == '\r' ||
+            x == '\n' || x == '\f' || x == '\v' ||
+            x == '\xa0'
+
+isNL : Char -> Bool
+isNL x = x == '\r' || x == '\n'
+
+toUpper : Char -> Char
+toUpper x = if (isLower x)
+               then (prim__intToChar (prim__charToInt x - 32))
+               else x
+
+toLower : Char -> Char
+toLower x = if (isUpper x)
+               then (prim__intToChar (prim__charToInt x + 32))
+               else x
+
+isHexDigit : Char -> Bool
+isHexDigit x = elem (toUpper x) hexChars where
+  hexChars : List Char
+  hexChars = ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
+              'A', 'B', 'C', 'D', 'E', 'F']