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Some Scala keywords are not recognized #118

Closed GoogleCodeExporter closed 9 years ago

GoogleCodeExporter commented 9 years ago 
The scala spec (http://www.scala-lang.org/docu/files/ScalaReference.pdf) 
mentions the following keywords:

abstract case catch class def
do else extends false final
finally for forSome if implicit
import lazy match new null
object override package private protected
requires return sealed super this
throw trait try true type
val var while with yield

Out of which the following are not recognized:
forSome lazy match requires trait type val

Original issue reported on code.google.com by christop...@gmail.com on 11 Jun 2010 at 9:23

GoogleCodeExporter commented 9 years ago 
I'm still learning Scala, but are you sure all of these are keywords.
Specifically, "match"?

Scala by example ( http://www.scala-lang.org/docu/files/ScalaByExample.pdf ) 
claims that it is a valid method name:

    Pattern matching is a generalization of C or Java’s switch
    statement to class hierarchies. Instead of a switch statement,
    there is a standard method match, which is defined in Scala’s
    root class Any, and therefore is available for all objects.

Maybe it should be highlit because of its special significance in common idioms 
either way.

Original comment by msam...@google.com on 11 Jun 2010 at 10:10

GoogleCodeExporter commented 9 years ago 
I am surprised by the quote you mention. If you look at the API, this method 
does not exist: http://www.scala-lang.org/docu/files/api/scala/Any.html . Maybe 
that's the way the pattern matching is or was implemented internally.

In the PDF you mention there is also a list of reserved words (page 29) which 
includes match. Strangely, that list is missing two words from the list that I 
mentionend: forSome and lazy. I suppose they are newer and were forgotten.

I tried to compile some code where I name a variable "match" which resulted in:
IsMatchAKeyword.scala:6: error: illegal start of simple pattern
                val match = 4;
                    ^

So it seems match really is a reserved word.

Original comment by christop...@gmail.com on 11 Jun 2010 at 10:46

GoogleCodeExporter commented 9 years ago 
I can confirm that it's not on Any in the scaladoc and 
http://lampsvn.epfl.ch/svn-repos/scala/scala/trunk/src/compiler/scala/tools/nsc/
ast/parser/Parsers.scala contains the comment

              | PostfixExpr match `{' CaseClauses `}'

which would seem to indicate "match" is a keyword.

The grammar that is spread throughout that class should provide the starting 
point for a lang-scala.js extension.

Original comment by msam...@google.com on 12 Jun 2010 at 12:57

GoogleCodeExporter commented 9 years ago 
From http://www.scala-lang.org/node/3419

Re: where is the machine-readable grammar for scala
Hi Greg,
I do not think the grammar exists anywhere as a whole, in the form you imply 
(EBNF?). But I have a few pointers that might be of help:
a) Scattered BNF fragments in:
http://lampsvn.epfl.ch/svn-repos/scala/scala/trunk/src/compiler/scala/tools/nsc/
ast/parser/Parsers.scala
Search for ::= in the Parsers.scala file

b) LaTeX-ized version of EBNF grammar in:
http://lampsvn.epfl.ch/svn-repos/scala/scala-documentation/trunk/src/reference/S
yntaxSummary.tex
c) Andrew Foggin's project:
http://code.google.com/p/scala-rules/
which builds a parser for the complete Scala grammar. AFAIK the Jetbrains gurus 
use(d) this stuff for the IDEA Scala plugin.
BRChristos

Original comment by mikesamuel@gmail.com on 21 Jul 2010 at 4:26

GoogleCodeExporter commented 9 years ago 
Added a scala mode at revision 108.
Please see 
http://google-code-prettify.googlecode.com/svn/trunk/tests/prettify_test.html#sc
ala

Original comment by mikesamuel@gmail.com on 21 Jul 2010 at 5:09