Hello, First of all, thank you for those who replied kindly.
When the -XUnicodeSyntax option is specified, GHC accepts some Unicode characters including left/right arrows. Unfortunately, the letter "greek lambda" cannot be used. Are there any technical reasons to not accept it?
The "greek lambda" is a normal lower-case alphabetic character - it can be used in identifier names.
OK. I understand.
But it could be a reserved word synonymous with \. After all, \ can occur in operator symbols, but the operator \ is reserved.
Presumably that would let you do (\ x -> ...) but not (\x -> ) since the "\x" would run together and lexically it would be one identifier.
If we reserve the greek lambda as special like '\', the lexer can separate <lambda>x into two tokens: <lambda> and 'x', I guess. Some people may want to use the greek lambda in identifiers. And some would want to use the greek lambda as an alternative of '\'. So, how about providing a new option to make the greek lambda special? P.S. I want to type the examples in "Programming in Haskell" as is. --Kazu