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Strand notation: Difference between revisions
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* In [[APL2]], [[APLX]] and others, arrays are stranded after operator evaluation and bracket indexing, but before function evaluation. | * In [[APL2]], [[APLX]] and others, arrays are stranded after operator evaluation and bracket indexing, but before function evaluation. | ||
* In [[APL\360]], [[SHARP APL]] and [[J]] stranding is called '''vector notation''' and is a part of token formation rather than execution. Only plain numbers are stranded. | * In [[APL\360]], [[SHARP APL]] and [[J]] stranding is called '''vector notation''' and is a part of token formation rather than execution. Only plain numbers are stranded. | ||
* In [[A+]] a system equivalent to APL\360 is implemented, but is described as part of [[numeric literal]] notation. "Stranding" in A+ refers to vector notation using parentheses and semicolons < | * In [[A+]] a system equivalent to APL\360 is implemented, but is described as part of [[numeric literal]] notation. "Stranding" in A+ refers to vector notation using parentheses and semicolons <syntaxhighlight lang=apl inline>(a;b;c)</syntaxhighlight>. | ||
* [[BQN]] breaks [[backwards compatibility]] with APL and does not allow stranding by juxtaposition even for numbers. Instead, the "ligature" character <code>‿</code> is used for a more explicit variation of stranding. | * [[BQN]] breaks [[backwards compatibility]] with APL and does not allow stranding by juxtaposition even for numbers. Instead, the "ligature" character <code>‿</code> is used for a more explicit variation of stranding. | ||
An example in which stranding interferes with the most obvious way of writing a program is shown below. Consider applying the function < | An example in which stranding interferes with the most obvious way of writing a program is shown below. Consider applying the function <syntaxhighlight lang=apl inline>f</syntaxhighlight> to <syntaxhighlight lang=apl inline>0.8</syntaxhighlight> three times using the [[Power operator]]: | ||
< | <syntaxhighlight lang=apl> | ||
f⍣3 0.8 | f⍣3 0.8 | ||
</syntaxhighlight> | </syntaxhighlight> | ||
In a language which strands before function application, this expression is equivalent to the derived function < | In a language which strands before function application, this expression is equivalent to the derived function <syntaxhighlight lang=apl inline>f⍣(3,0.8)</syntaxhighlight>. Not what was intended! The two numbers must be separated somehow, for instance with parentheses or a [[Identity|tack function]]. | ||
< | <syntaxhighlight lang=apl> | ||
(f⍣3)0.8 | (f⍣3)0.8 | ||
f⍣3⊢0.8 | f⍣3⊢0.8 | ||
</syntaxhighlight> | </syntaxhighlight> | ||
For operators that take array operands, such as the [[Rank operator]], stranding before operator application can be beneficial. Without it, a function with two ranks such as < | For operators that take array operands, such as the [[Rank operator]], stranding before operator application can be beneficial. Without it, a function with two ranks such as <syntaxhighlight lang=apl inline>⊥⍤0 1</syntaxhighlight> would have to be written with parentheses <syntaxhighlight lang=apl inline>⊥⍤(0 1)</syntaxhighlight>. | ||
== External links == | == External links == | ||