Encode variances in parameter names #2103
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This leads to a slight overall simplification, harmonizes pickle format with internal representation, and makes MethodTypes and PolyTypes more similar to each other. I believe the change is useful as it is, but in particular it is a useful step for an eventual unification of MethodTypes and PolyTypes.
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That's a very nice simplification! |
smarter
reviewed
Mar 14, 2017
| @@ -241,6 +241,12 @@ object desugar { | |||
| * class C { type v C$T; type v T = C$T } | |||
| */ | |||
| def typeDef(tdef: TypeDef)(implicit ctx: Context): Tree = { | |||
| val name = | |||
| if (tdef.name.hasVariance && tdef.mods.is(Param)) { | |||
| ctx.error(em"type parameter name may not start with `+' or `-'", tdef.pos) | |||
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Is this even allowed by the parser?
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Yes, ++, -- are legal parameter names.
smarter
reviewed
Mar 14, 2017
| class PolyType(val paramNames: List[TypeName], val variances: List[Int])( | ||
| /** A type lambda of the form `[X_0 B_0, ..., X_n B_n] => T` | ||
| * This is used both as a type of a polymorphic method and as a type of | ||
| * a higher-kidned type parameter. Variances are encoded in parameter |
and fix typo
It was a red herring. Symbolic names are expanded anyway to $plus / $minus, so they can't be confused with a variance prefix.
Merged
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Superseded by #2121 |
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This leads to a slight overall simplification, harmonizes pickle
format with internal representation, and makes MethodTypes and
PolyTypes more similar to each other.
I believe the change is useful as it is, but in particular it is
a useful step for an eventual unification of MethodTypes and
PolyTypes.