/usr/share/javascript/prettify/lang-hs.js is in libjs-prettify 2013.03.04+dfsg-4.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 | PR.registerLangHandler(PR.createSimpleLexer([["pln",/^[\t\n\x0B\x0C\r ]+/,null,"\t\n\x0B\f\r "],["str",/^\"(?:[^\"\\\n\x0C\r]|\\[\s\S])*(?:\"|$)/,null,'"'],["str",/^\'(?:[^\'\\\n\x0C\r]|\\[^&])\'?/,null,"'"],["lit",/^(?:0o[0-7]+|0x[\da-f]+|\d+(?:\.\d+)?(?:e[+\-]?\d+)?)/i,null,"0123456789"]],[["com",/^(?:(?:--+(?:[^\r\n\x0C]*)?)|(?:\{-(?:[^-]|-+[^-\}])*-\}))/],["kwd",/^(?:case|class|data|default|deriving|do|else|if|import|in|infix|infixl|infixr|instance|let|module|newtype|of|then|type|where|_)(?=[^a-zA-Z0-9\']|$)/,
null],["pln",/^(?:[A-Z][\w\']*\.)*[a-zA-Z][\w\']*/],["pun",/^[^\t\n\x0B\x0C\r a-zA-Z0-9\'\"]+/]]),["hs"]);
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