Ex1: TYPE definitions

[Chris Walton]

Simplest type

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TYPE data_type POSSREP { value CHAR };

Inheritance from built-in type

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TYPE Ntest2 IS { INTEGER  CONSTRAINT INTEGER < 10 };

Union type

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TYPE data_type UNION;

Union type with own possrep

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TYPE data_type UNION POSSREP { domain ID, name ID, T ID };

Specialisation by constraint

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TYPE art IS { data_type POSSREP { T ID CONSTRAINT THE_VALUE ( T ) = "art" } };

Inheritance by extension

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TYPE two IS { data_type POSSREP { T ID } };

Subtypes of a union type

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TYPE arbitrary_defn IS { data_type POSSREP { 
  domain ID, name ID, T ID CONSTRAINT  THE_T ( T ) = ID ( "arbitrary_defn" ) } };
TYPE boolean_defn IS { data_type POSSREP {
  domain ID, name ID, T ID CONSTRAINT  THE_T ( T ) = ID ( "boolean_defn" ) } };

[steved]

Hi,

I'm just starting to explore user defined types in Rel. I found these
examples helpful.

thanks,
steve