On 22/04/13 4:29 PM, Andreas Rossberg wrote: > On Apr 22, 2013, at 03:31 , Michael Norrish > <michael.norr...@nicta.com.au> wrote: >> Is the following really supposed to be acceptable? Both Poly/ML and >> mlton accept it without complaining: >> >> datatype '+ = C | D; >> >> (Moscow ML rejects it. mlton and Poly/ML treat it as the >> declaration of a unary type operator called +.) >> >> and what about >> >> datatype '' foo = C | D; > > MLton and Poly/ML are correct. A type variable can be named plain ' > or '', and symbolic identifiers (except *) are allowed as type > names.
Wow; you learn something new everyday. Thanks for the quick feedback. Incidentally, I think that makes your grammar at http://www.mpi-sws.org/~rossberg/sml.html incorrect: the grammar there wants an <id> to follow the apostrophe for <var>, and <id>s have at least one character in them. Best, Michael
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