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Glyphs are the individual characters and symbols used in APL, primarily to represent [[primitive function|primitive functions]] and [[primitive operator|operators]].
Glyphs are the individual characters and symbols used in APL, primarily to represent [[primitive function]]s and [[primitive operator|operators]]. A glyph is distinct from the functionality it represents, and usually has a different name: for example, the [[dyadic]] function [[Take]] is represented with the glyph [[Up Arrow]].


Prior to the widespread adoption of [[wikipedia:Unicode|Unicode]], many special-purpose code pages were used to represent APL symbols (see [[Wikipedia: Digital encoding of APL symbols]]).
Most of APL's glyphs cannot be represented in [[wikipedia:ASCII|ASCII]], now considered a "standard" or "basic" character set, but all of them are included in [[Unicode]], as one goal of Unicode was to unify existing character sets. In fact, [[Ken Iverson]] first began using [[Iverson notation|his notation]] before work on ASCII began, and [[APL\360]] was implemented before the modern ASCII standard was published in 1967. Prior to the widespread adoption of Unicode, many [[wikipedia:Digital encoding of APL symbols|special purpose code pages]] were used to represent APL symbols. APLs developed more recently, such as [[NARS2000]] and [[GNU APL]], use Unicode characters to represent glyphs, sometimes supporting several different options for a given glyph. Unicode also offers the possibility of introducing glyphs that could not have been produced on older APL systems: for example, both [[NARS2000]] and [[dzaima/APL]] use <source lang=apl inline>√</source> for the [[Square Root]] and [[Root]] functions.
 
Because of difficulties associated with non-ASCII characters (while display problems have been almost eliminated by Unicode, entering the characters may still be a barrier), several array-family languages such as [[J]], [[K]], and [[ELI]] have chosen to encode the language using only ASCII, either by reducing and compacting functionality to use one character per glyph or by using multiple characters in some cases (in J, these are called "bigraphs" and "trigraphs"). Historically there have also been various encodings of APL in smaller character sets, typically as an alternate way of writing code for an APL with traditional glyphs.
 
While [[Iverson notation]] was originally handwritten, the choice of glyphs to include in the first APL implementations was influenced by technical constraints of the typewriters used at the time. Notably, many glyphs were produced by overlaying two simpler glyphs, a technique known as [[Overstrike|overstriking]].


{{APL features}}
{{APL features}}
{{APL glyphs}}
[[Category:Glyphs| ]]

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