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digitalmars.D - D grammar oddities

reply Dibyendu Majumdar <d.majumdar gmail.com> writes:
struct and unions aren't types.
function and delegate are not either.

According to the grammar.
Nov 16 2020
next sibling parent "H. S. Teoh" <hsteoh quickfur.ath.cx> writes:
On Mon, Nov 16, 2020 at 11:55:29PM +0000, Dibyendu Majumdar via Digitalmars-d
wrote:

 struct and unions aren't types.
 function and delegate are not either.
 
 According to the grammar.


Link?


T

-- 
Creativity is not an excuse for sloppiness.
Nov 16 2020
prev sibling next sibling parent reply Paul Backus <snarwin gmail.com> writes:
On Monday, 16 November 2020 at 23:55:29 UTC, Dibyendu Majumdar 
wrote:

 struct and unions aren't types.
 function and delegate are not either.

 According to the grammar.


A struct declaration *creates* a type, but it is not, itself, a 
type. When you declare `struct MyStruct { /* ... */ }`, the type 
that's created is just called `MyStruct`--which means that, 
grammatically, the type is an identifier.
Nov 16 2020
parent reply Dibyendu Majumdar <mobile majumdar.org.uk> writes:
On Tuesday, 17 November 2020 at 00:24:20 UTC, Paul Backus wrote:


 A struct declaration *creates* a type, but it is not, itself, a 
 type. When you declare `struct MyStruct { /* ... */ }`, the 
 type that's created is just called `MyStruct`--which means 
 that, grammatically, the type is an identifier.


Sure - but the issue is the grammar is useless for trying to 
understand the language.

There is a production Types -> .... But it isn't map to a type.

https://dlang.org/spec/grammar.html#types
Nov 17 2020
parent reply Dibyendu Majumdar <mobile majumdar.org.uk> writes:
On Tuesday, 17 November 2020 at 22:01:16 UTC, Dibyendu Majumdar 
wrote:

 On Tuesday, 17 November 2020 at 00:24:20 UTC, Paul Backus wrote:


 A struct declaration *creates* a type, but it is not, itself, 
 a type. When you declare `struct MyStruct { /* ... */ }`, the 
 type that's created is just called `MyStruct`--which means 
 that, grammatically, the type is an identifier.


 Sure - but the issue is the grammar is useless for trying to 
 understand the language.

 There is a production Types -> .... But it isn't map to a type.

 https://dlang.org/spec/grammar.html#types


wrong link - sorry - just look for Type production in the grammar
Nov 17 2020
parent Paul Backus <snarwin gmail.com> writes:
On Tuesday, 17 November 2020 at 22:04:34 UTC, Dibyendu Majumdar 
wrote:

 Sure - but the issue is the grammar is useless for trying to 
 understand the language.

 There is a production Types -> .... But it isn't map to a type.

 https://dlang.org/spec/grammar.html#types


 wrong link - sorry - just look for Type production in the 
 grammar


I assume this is the production you mean:

https://dlang.org/spec/grammar.html#Type

I don't understand why you'd say that this is "useless." It is 
perfectly useful if you want to understand how to refer to a type 
syntactically--for example, in a variable declaration, or when 
passing it as an argument to a template.

Is your complaint that a description of the language's *syntax* 
does not do anything to help you understand its *semantics*? If 
so, that's certainly true, but I'm not sure why you'd expect it 
to. The job of the grammar is only to explain the language's 
syntax. Explaining the semantics of D is what the other pages in 
the language spec are for.
Nov 17 2020
prev sibling parent user1234 <user1234 12.de> writes:
On Monday, 16 November 2020 at 23:55:29 UTC, Dibyendu Majumdar 
wrote:

 struct and unions aren't types.


Correct, They are declarations. For their declarations an 
internal TypeStruct / TypeUnion is created. Later Identifier are 
resolved to those TypeQualified.


 function


Same principle. Function are declarations and an internal 
TypeFunction is created for the decl.

In addition when there's a need to express a function type, an 
alias must be used, for example:

alias F = void(int);


 and delegate are not either.


they are. But it's hidden as type suffix:

https://dlang.org/spec/declaration.html#TypeSuffixes

        void           delgate (int)
-------^     ---------^
BasicType    TypeSuffix



 According to the grammar.
Nov 16 2020