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Quad name: Difference between revisions
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|{{quote | "The quad <source lang=apl inline>⎕</source> can be used to define the geometries of the other APL characters, since all the APL characters can be described by their relationship to it. The quad character was originally chosen for the font so that it could be used around any of the other characters. In particular, it was chosen to be a size such that it fit around any of the alphabetic characters. For example, the top of the bottom line of the quad is the base line of the alphabetic and numeric characters, and the bottom of the top of the quad is their top. The geometric center of the quad is the center of many of the APL special symbols. In particular, function symbols are normally raised above the baseline of characters — this position is known as the "function center." It is interesting to note that the dimensions of the quad are the "golden section" which is a well-accepted esthetic criterion in art and design."|Joey K. Tuttle. ''APL pi — designing an APL type font'', 1981.}} | |||
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A '''quad name''' or ''system name'' is a general term for built-ins denoted by a name beginning with the quad character, <source lang=apl inline>⎕</source>. The term only used when explicitly needing to cover all syntactic classes of such built-ins; constants, variables, objects, functions and operators. It is common to call these ''system constants'', ''system variables'', etc., although the term ''system function'' is often used as a synonym for ''quad name''. Quad names are used for features that abide by the normal syntax, but are not part of the core language. <source lang=apl inline>⎕</source> by itself (standard output/evaluated input) and <source lang=apl inline>⍞</source> (message output/standard input) are often included in the quad name category. | A '''quad name''' or ''system name'' is a general term for built-ins denoted by a name beginning with the quad character, <source lang=apl inline>⎕</source>. The term only used when explicitly needing to cover all syntactic classes of such built-ins; constants, variables, objects, functions and operators. It is common to call these ''system constants'', ''system variables'', etc., although the term ''system function'' is often used as a synonym for ''quad name''. Quad names are used for features that abide by the normal syntax, but are not part of the core language. <source lang=apl inline>⎕</source> by itself (standard output/evaluated input) and <source lang=apl inline>⍞</source> (message output/standard input) are often included in the quad name category. | ||
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* System variables are used to alter the behaviour of the language. For example the number of significant digits displayed can be controlled by setting the [[print precision]] (<source lang=apl inline>⎕PP</source>). | * System variables are used to alter the behaviour of the language. For example the number of significant digits displayed can be controlled by setting the [[print precision]] (<source lang=apl inline>⎕PP</source>). | ||
* System objects are references to namespaces, in particular the session object (<source lang=apl inline>⎕SE</source>). | * System objects are references to namespaces, in particular the session object (<source lang=apl inline>⎕SE</source>). | ||
* System functions are various utility functions, like | * System functions are various utility functions, like <source lang=apl inline>⎕FX</source> to define ("FiX") a function under program control. | ||
* System operators only occur in [[Dyalog APL]] and are used for things like text search and replace (<source lang=apl inline>⎕S</source> and <source lang=apl inline>⎕R</source>). | * System operators only occur in [[Dyalog APL]] and are used for things like text search and replace (<source lang=apl inline>⎕S</source> and <source lang=apl inline>⎕R</source>). | ||
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* [http://help.dyalog.com/latest/#Language/System%20Functions/Summary%20Tables/Introduction.htm Dyalog] | * [http://help.dyalog.com/latest/#Language/System%20Functions/Summary%20Tables/Introduction.htm Dyalog] | ||
* [http://microapl.com/apl_help/ch_020_070.htm APLX] | * [http://microapl.com/apl_help/ch_020_070.htm APLX] | ||
{{APL features}} | {{APL features}}[[Category:APL syntax]] | ||