Statement separator: Difference between revisions
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Statement Separator | {{Built-in|Statement Separator|⋄}} often called by the name of its glyph, '''Diamond''', allows placing multiple statements on a single line. It works both inside a function and directly within the interpreter. Empty statements are generally ignored. | ||
== Description == | |||
The Statement Separator forces the interpreter to read from left to right. Each separate statement will be read as if on its own line. | |||
[[A Dictionary of APL]]<ref>[[Kenneth E. Iverson|Iverson, Kenneth]]. [https://www.jsoftware.com/papers/APLDictionary1.htm#3e "A Dictionary of APL"]. Sansom. 1987.</ref> states that "expressions using the statement separator (<syntaxhighlight lang=apl inline>⋄</syntaxhighlight>) can be mimicked by expressions using the verb '''[[left]]'''. The primary difference is that the separation imposed by <syntaxhighlight lang=apl inline>⊣</syntaxhighlight> follows the normal rules for order of execution." | |||
[[ | Some historical APLs used a right-to-left alternative [[glyph]] to achieve the same effect as the left [[Identity]] function (<syntaxhighlight lang=apl inline>⊣</syntaxhighlight>), as does [[J]] (<syntaxhighlight lang=j inline>[</syntaxhighlight>). | ||
* [[APL/700]] used a semicolon (<syntaxhighlight lang=apl inline>;</syntaxhighlight>) | |||
* [[MCM/70]] used a "null operator" [[jot]] (<syntaxhighlight lang=apl inline>∘</syntaxhighlight>) | |||
However, and while relevant for J, but not for these historical APLs, this does not allow definition of multiple single-line functions on the same line. | |||
[[Branch]] (<syntaxhighlight lang=apl inline>→</syntaxhighlight>) takes precedence over statement separators. "If the expression to the right of the branch is not empty, the system goes immediately to the line whose number is the first element in that expression."<ref>[[Paul Berry|Berry, Paul]]. [https://archive.org/details/sharp-apl-reference-manual_202108 "Sharp APL Reference Manual"]. [[I.P. Sharp Associates]]. 1987.</ref> It is only possible to branch to the first statement on any line. | |||
When | When displaying an errors message, where the error happened on a line containing statement separators, statements to the right of the position indicated by the error caret have not yet been executed: | ||
<syntaxhighlight lang=apl> | |||
DOMAIN ERROR: Divide by zero | |||
2÷0 ⋄ 1+3 | |||
∧ | |||
</syntaxhighlight> | |||
Statement separators to the right of a [[comment]] are ignored. | Statement separators to the right of a [[comment]] <syntaxhighlight lang=apl inline>⍝</syntaxhighlight> are part of the command are therefore ignored. | ||
== Examples == | == Examples == | ||
| Line 24: | Line 33: | ||
=== Documentation === | === Documentation === | ||
* | * [https://help.dyalog.com/latest/index.htm#Language/Defined%20Functions%20and%20Operators/TradFns/Statements.htm Dyalog] | ||
* | * [https://microapl.com/apl_help/ch_020_020_930.htm APLX] | ||
* | * [http://wiki.nars2000.org/index.php?title=Diamond NARS2000] | ||
* | * [https://mlochbaum.github.io/BQN/doc/token.html#separators BQN] (<syntaxhighlight lang=apl inline>⋄</syntaxhighlight> and <syntaxhighlight lang=apl inline>,</syntaxhighlight> are synonymous) | ||
== References == | == References == | ||
<references /> | <references /> | ||
{{APL | {{APL syntax}}[[Category:APL syntax]] | ||
Latest revision as of 05:24, 11 November 2022
⋄
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Statement Separator (⋄) often called by the name of its glyph, Diamond, allows placing multiple statements on a single line. It works both inside a function and directly within the interpreter. Empty statements are generally ignored.
Description
The Statement Separator forces the interpreter to read from left to right. Each separate statement will be read as if on its own line.
A Dictionary of APL[1] states that "expressions using the statement separator (⋄) can be mimicked by expressions using the verb left. The primary difference is that the separation imposed by ⊣ follows the normal rules for order of execution."
Some historical APLs used a right-to-left alternative glyph to achieve the same effect as the left Identity function (⊣), as does J ([).
However, and while relevant for J, but not for these historical APLs, this does not allow definition of multiple single-line functions on the same line.
Branch (→) takes precedence over statement separators. "If the expression to the right of the branch is not empty, the system goes immediately to the line whose number is the first element in that expression."[2] It is only possible to branch to the first statement on any line.
When displaying an errors message, where the error happened on a line containing statement separators, statements to the right of the position indicated by the error caret have not yet been executed:
DOMAIN ERROR: Divide by zero
2÷0 ⋄ 1+3
∧
Statement separators to the right of a comment ⍝ are part of the command are therefore ignored.
Examples
Statements are read from left to right:
A←10 ⋄ A←A×3 ⋄ A÷2 15
External links
Documentation
References
- ↑ Iverson, Kenneth. "A Dictionary of APL". Sansom. 1987.
- ↑ Berry, Paul. "Sharp APL Reference Manual". I.P. Sharp Associates. 1987.