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I-Beam: Difference between revisions
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{{Built-in|I-Beam|⌶}} is a [[primitive operator|primitive]] [[monadic operator]] that takes a numeric code as | {{Built-in|I-Beam|⌶}} is a [[primitive operator|primitive]] [[ambivalent function]] or [[monadic operator]] that takes a numeric code as an [[argument]]/[[operand]] and provides a range of ad-hoc operations. This range covers non-[[primitive function]]s, for example experimental features, interpreter-level control, access to the environment, and information about APL itself. | ||
== History == | == History == | ||
I-Beam was introduced in [[APL\360]] | I-Beam was introduced in [[APL\360]] as an [[ambivalent function]] for implementers to execute [[wikipedia:IBM System/360|IBM System/360]] (''I-Beam'' being pronounced very similarly to ''IBM'') instructions from program control. The convenience of this lead to I-Beam becoming directly available for use by anyone.<ref>[https://dl.acm.org/doi/pdf/10.1145/585923.585925 The Design of APL]</ref> However, modern IBM-derived APLs replace all I-Beams with [[quad name]]s. For example, <syntaxhighlight lang=apl inline>5⌶</syntaxhighlight> became <syntaxhighlight lang=apl inline>⎕DL</syntaxhighlight> ([[Delay]]) while changing time unit from [[wikipedia:jiffy|jiffies]] of 1⁄300<sup>th</sup> of a second to a whole second. | ||
Later, after it became common to use arrays as operands, [[Dyalog APL]] began using the [[glyph]] as an operator where the operand selects functionality. It is used for testing experimental features, some of which may eventually become primitives or quad name. For example, <syntaxhighlight lang=apl inline>819⌶</syntaxhighlight> became <syntaxhighlight lang=apl inline>⎕C</syntaxhighlight> ([[Case Convert]]), while introducing distinction between case folding (for case insensitive comparisons) and case mapping (for human presentation forms). | |||
== Mnemonics == | == Mnemonics == | ||
In general, I-Beam's numeric operand isn't intended to be easily recalled. But some are given meaningful names. | In general, I-Beam's numeric operand isn't intended to be easily recalled. But some are given meaningful names. | ||
One method is to devise a name from the [[wikipedia:Roman numerals|Roman numeral]] letters I, V, X, L, C, D, and M<ref>[https://www.dyalog.com/blog/2016/06/i-beam-mnemonics/ I-Beam Mnemonics]</ref> | One method is to devise a name from the [[wikipedia:Roman numerals|Roman numeral]] letters I, V, X, L, C, D, and M:<ref>[https://www.dyalog.com/blog/2016/06/i-beam-mnemonics/ I-Beam Mnemonics]</ref> | ||
{|class=wikitable | {|class=wikitable | ||
! I-Beam !! Numeral | ! I-Beam !! Numeral | ||
|- | |||
| Colour Coding || CC (200) | |||
|- | |||
| Colour Coding Information || CCI (201) | |||
|- | |- | ||
| Called Monadically || CM (900) | | Called Monadically || CM (900) | ||