#5108: Allow unicode sub/superscript symbols in both identifiers and operators
-----------------------------------+----------------------------------------
Reporter: mikhail.vorozhtsov | Owner:
Type: feature request | Status: new
Priority: normal | Component: Compiler
Version: 7.1 | Keywords: lexer unicode
Testcase: | Blockedby:
Os: Unknown/Multiple | Blocking:
Architecture: Unknown/Multiple | Failure: None/Unknown
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While #4373 permits
{{{
Prelude> let vā = 1
}}}
the following is rejected
{{{
Prelude> let m >>=ā f = undefined
<interactive>:0:10: lexical error at character '\8321'
}}}
Identifiers with non-numeric subscripts are not accepted either:
{{{
Prelude> let vā = 1
<interactive>:0:6: lexical error at character '\8336'
}}}
I wrote a small patch that makes such definitions possible.
1. A new unicode Alex macro, {{{$subsup}}}, is introduced and added to
{{{$idchar}}}, {{{$symchar}}}, and {{{$graphic}}}
2. A unicode code point is classified as {{{$subsup}}} by
{{{alexGetChar}}} iff either of the following holds:
a. The code point is annotated with <sub> or <super> in
[http://www.unicode.org/Public/UNIDATA/UnicodeData.txt]
b. It is the [DOUBLE/TRIPLE/QUADRUPLE] PRIME (U+2032, U+2033, U+2034,
U+2057)
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5108>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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