1
Scala
Scala's Type System: a tutorial
DATE: 2012/04/01::
2
Type-ZERO - All Systems Nominal (MechWarrior Online Tribute)
Type-ZERO - All Systems Nominal (MechWarrior Online Tribute)
DATE: 2013/01/02::
3
All Systems Nominal: Episode #6 - Retroactive
All Systems Nominal: Episode #6 - Retroactive
DATE: 2014/11/04::
4
Data Types C# - common language runtime types, nominal storage allocation, and value range
Data Types C# - common language runtime types, nominal storage allocation, and value range
DATE: 2014/09/26::
5
All Systems Nominal: CW Chapter 1
All Systems Nominal: CW Chapter 1
DATE: 2015/02/04::
6
Systems Nominal (Anything But)
Systems Nominal (Anything But)
DATE: 2014/12/23::
7
All Systems Nominal: Episode #1 - Watchful Cicada
All Systems Nominal: Episode #1 - Watchful Cicada
DATE: 2013/02/01::
8
[MWO] All Systems Nominal
[MWO] All Systems Nominal
DATE: 2012/11/09::
9
All Systems Nominal: Episode #2 - Fright Night
All Systems Nominal: Episode #2 - Fright Night
DATE: 2013/02/23::
10
Nominal versus Real GDP
Nominal versus Real GDP
DATE: 2012/01/25::
11
Systems Nominal | Nerd³
Systems Nominal | Nerd³'s Early Christmas Present
DATE: 2014/12/24::
12
All Systems Nominal: Episode #3 - Equilibrium
All Systems Nominal: Episode #3 - Equilibrium
DATE: 2013/03/31::
13
All systems nominal
All systems nominal
DATE: 2013/09/28::
14
Top 30 Richest Countries in Africa by GDP Nominal
Top 30 Richest Countries in Africa by GDP Nominal
DATE: 2014/05/16::
15
All Systems Nominal
All Systems Nominal
DATE: 2012/06/20::
16
Trust Gxt 38 2.1 Speaker System
Trust Gxt 38 2.1 Speaker System
DATE: 2015/01/31::
17
systems nominal new hack 2015
systems nominal new hack 2015
DATE: 2014/12/23::
18
AMADA/WASINO G-05 2-AXIS CNC HIGH SPEED GANG TYPE CHUCKER WITH GANTRY LOADING SYSTEM
AMADA/WASINO G-05 2-AXIS CNC HIGH SPEED GANG TYPE CHUCKER WITH GANTRY LOADING SYSTEM
DATE: 2014/11/05::
19
[DOWNLOAD] MW3 Reactor online, sensors online, weapons online, all systems nominal
[DOWNLOAD] MW3 Reactor online, sensors online, weapons online, all systems nominal
DATE: 2012/03/10::
20
JL Audio 1000/1 Dyno 2.8 ohm nominal
JL Audio 1000/1 Dyno 2.8 ohm nominal
DATE: 2014/08/24::
21
HI-TEX Active spekers, Hornsonic
HI-TEX Active spekers, Hornsonic
DATE: 2011/04/17::
22
PylePro PDWM3400 Premier Series UHF Microphone System with 2 Body-Pack Transmitters 2 Headsets
PylePro PDWM3400 Premier Series UHF Microphone System with 2 Body-Pack Transmitters 2 Headsets
DATE: 2015/01/26::
23
Golden Rules of Accounting,how to understand the concepts of Real,Personal and Nominal account rules
Golden Rules of Accounting,how to understand the concepts of Real,Personal and Nominal account rules
DATE: 2013/09/05::
24
DIATONE DS-77Z
DIATONE DS-77Z
DATE: 2014/06/12::
25
Logitech X530 PC Multimedia Home Theatre Speaker System 70 Watt Total 5.1
Logitech X530 PC Multimedia Home Theatre Speaker System 70 Watt Total 5.1
DATE: 2012/02/23::
26
A Video about Variable Levels: Nominal, Ordinal, Interval, & Ratio
A Video about Variable Levels: Nominal, Ordinal, Interval, & Ratio
DATE: 2013/03/29::
27
Logitech Z 506 Speaker System
Logitech Z 506 Speaker System
DATE: 2012/01/28::
28
PylePro PDWM3400 Premier Series UHF Microphone System with 2 Body-Pack Transmitters 2 Headsets
PylePro PDWM3400 Premier Series UHF Microphone System with 2 Body-Pack Transmitters 2 Headsets
DATE: 2015/01/26::
29
How to Use SPSS: Oraganizing,Coding and Entering Data for Non-Parametric Data Analysis
How to Use SPSS: Oraganizing,Coding and Entering Data for Non-Parametric Data Analysis
DATE: 2013/08/28::
30
Creative T6160 5.1 Unboxing
Creative T6160 5.1 Unboxing
DATE: 2011/01/14::
31
Assembleon (Philips) Gem Series Topaz Placement System
Assembleon (Philips) Gem Series Topaz Placement System
DATE: 2011/07/18::
32
How to Select the Right FRAM (F-RAM) for your Applications
How to Select the Right FRAM (F-RAM) for your Applications
DATE: 2013/10/21::
33
How to tell if your Samsung Galaxy S3 CPU is fast, nominal or slow.
How to tell if your Samsung Galaxy S3 CPU is fast, nominal or slow.
DATE: 2013/02/22::
34
NEW Subaru WRX STI 2015 Impreza official video
NEW Subaru WRX STI 2015 Impreza official video
DATE: 2014/01/14::
35
AEMC® - PEL App For Android™
AEMC® - PEL App For Android™
DATE: 2014/08/08::
36
Multi strand system.avi
Multi strand system.avi
DATE: 2012/03/30::
37
JBL EON 210P Portable PA System @ Namm 2012 with DJkit.tv
JBL EON 210P Portable PA System @ Namm 2012 with DJkit.tv
DATE: 2012/01/31::
38
SELF-EXPANDING NITINOL STENT "JAGUAR" with delivery system
SELF-EXPANDING NITINOL STENT "JAGUAR" with delivery system
DATE: 2014/02/28::
39
Airtronics MT-4 Unboxing
Airtronics MT-4 Unboxing
DATE: 2014/06/23::
40
Razor MX650 (+LiFePO4) First Winter Ride - way
Razor MX650 (+LiFePO4) First Winter Ride - way 'Hobby marketplace - Preobrazhenskaya Ploschad'
DATE: 2014/12/14::
41
Trust 5.1 Surround Speaker Set SP-6250Z
Trust 5.1 Surround Speaker Set SP-6250Z
DATE: 2011/10/04::
42
Edifer S730 2.1 Speaker System
Edifer S730 2.1 Speaker System
DATE: 2015/04/25::
43
My CRAIGSLIST FIND FOR TODAY
My CRAIGSLIST FIND FOR TODAY
DATE: 2014/06/01::
44
HOW Mad Mimi: Gaining & Keeping Clients using RFPs with Janine Gregor
HOW Mad Mimi: Gaining & Keeping Clients using RFPs with Janine Gregor
DATE: 2015/01/07::
45
PROpak Portable Foam System
PROpak Portable Foam System
DATE: 2014/05/16::
46
KRK KNS 8400 Unboxing
KRK KNS 8400 Unboxing
DATE: 2012/05/18::
47
NEW 2014 BMW R 1200 GS Adventure Wethead
NEW 2014 BMW R 1200 GS Adventure Wethead
DATE: 2014/01/31::
48
Logitech X-140 Speakers Unboxing & Inside Look
Logitech X-140 Speakers Unboxing & Inside Look
DATE: 2009/09/25::
49
Rosetta
Rosetta's twelve-year journey in space
DATE: 2013/10/14::
50
LCM Landing Craft Mechanized Type 8 on GovLiquidation.com
LCM Landing Craft Mechanized Type 8 on GovLiquidation.com
DATE: 2014/03/20::
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From Wikipedia, the free encyclopedia
  (Redirected from Nominative type system)
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In computer science, a nominal or nominative type system (or name-based type system) is a major class of type system, in which compatibility and equivalence of data types is determined by explicit declarations and/or the name of the types. Nominal systems are used to determine if types are equivalent, as well as if a type is a subtype of another. It contrasts with structural systems, where comparisons are based on the structure of the types in question and do not require explicit declarations.

Nominal typing[edit]

Nominal typing means that two variables are type-compatible if and only if their declarations name the same type. For example, in C++, two struct types with different names are never considered compatible, even if they have identical field declarations.

However, C++ also allows a typedef declaration, which introduces an alias for an existing type. These are merely syntactical and do not differentiate the type from its alias for the purpose of type checking. This feature, present in many languages, can result in a loss of type safety when (for example) the same primitive integer type is used in two semantically distinct ways. Haskell provides the C-style syntactic alias, as well as a declaration that does introduce a new, distinct type, isomorphic to an existing type.

Nominal subtyping[edit]

In a similar fashion, nominal subtyping means that one type is a subtype of another if and only if it is explicitly declared to be so in its definition. Nominally-typed languages typically enforce the requirement that declared subtypes be structurally compatible (though Eiffel allows non-compatible subtypes to be declared). However, subtypes which are structurally compatible "by accident", but not declared as subtypes, are not considered to be subtypes.

C++, C#, Java, Objective-C, Delphi and Swift all primarily use both nominal typing and nominal subtyping.

Some nominally-subtyped languages, such as Java and C#, allow classes to be declared final (or sealed in C# terminology), indicating that no further subtyping is permitted.

Comparison[edit]

Nominal typing is useful at preventing accidental type equivalence, and is considered[by whom?] to have better type-safety than structural typing. The cost is a reduced flexibility, as, for example, nominal typing does not allow new super-types to be created without modification of the existing subtypes.

See also[edit]

Notes[edit]

References[edit]

External links[edit]

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