As in the Haskell Language Report, Haskell comments are valid whitespace. In addition, lines (which must end with a line feed character) that begin as follows are valid whitespace in source code, except immediately after a where, let, do or of keyword:
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#!. This accommodates ‘shebang’ interpreter directives in scripts on Unix-like operating systems. -
<space>#!, where<space>is an initial space character before the ‘shebang’. -
#pragma. This accommodates the use of a directive that passes additional information to a compiler. -
#line <line> "<file>", where<line>is a positive integer and<file>can comprise zero or more characters. This accommodates a compiler directive that resets the numbering of lines of source code, and the identification of the source code file name, in compiler messages. -
#<line> "<file>", where<line>is a positive integer and<file>can comprise zero or more characters.