Diamond: Difference between revisions

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<h1> {diamond} &mdash; Statement separator &mdash; Keystroke ALT+` (Accent grave) &mdash; Character 8900 or x22C4</h1>
{{Article header
|sym={diamond}
|def=Statement separator
|ks=ALT+` (Accent grave)
|char=8900 or x22C4
|kb=[[File:APLKB-Diamond.png]]}}
 
==Usage==
==Usage==
The diamond symbol <big>{diamond}</big> is used to start a new statement on the same line. It is used similarly to the ; in C, Pascal, PHP and many other languages, or the : or \ in some versions of Basic.
While the diamond operator ('''<big><big>{diamond}</big></big>''') can be used in an immediate statement to the Session Manager, it is most commonly used in a [[functions|function]] to start a new statement '''on the same''' physical line-row of user-code. It is used similarly to the semi colon ('''<big>;</big>''') in C, Pascal, PHP and many other languages, or the colon ('''<big>:</big>''') and backslash ('''<big>\</big>''') in some versions of Basic. It allows another statement to be concisely set on the same line.
==Example==
 
In this example, the variable K is tested to see if it is greater than or equal to 1. If the test fails, k is set to 1.<br/>
'''Note:''' The '''<big><big>{diamond}</big></big>''' operator <u>cannot</u> be used after a [[lamp]] (<big><big>{lamp}</big></big>) comment operator appears on the same line, as all characters after <big><big>{lamp}</big></big> are ignored.
:<code><big>{goto}(k{ge}1)/Xr {diamond} K{:=}1<br/>Xr:</big></code><br/>
 
'''Also note''' the '''<big><big>{diamond}</big></big>''' operator represents an <u>exception to the rule</u> that APL's interpreter executes from right to left, since the ''leftmost APL statement'' is executed BEFORE the adjacent APL statement after the next '''<big><big>{diamond}</big></big>''' operator and so on. Each APL statement is executed sequentially '''as if''' listed on multiple lines. The '''<big><big>{diamond}</big></big>''' operator also helps ''condense'' APL code since fewer ''visual'' lines will contain the same amount of APL coding - and in many instances it ''can result'' in cleaner, or easier-to-read-and-understand APL code.
 
==Examples==
In the first example, the variable K is tested to see if it is greater than or equal to 1. If the test fails, k is set to 1.<br/>
:<code><big>{goto}(k{ge}1)/Xr {diamond} K{:=}1<br/>Xr: &nbsp; &nbsp; ⍝This branch/goto Label is deliberately placed <u>first</u> on its own line!</big></code><br/>
It is the same as
It is the same as
:<code><big>{goto}(k{ge}1)/Xr <br/> K{:=}1<br/>Xr:</big></code><br/>
:<code><big>{goto}(k{ge}1)/Xr <br/> K{:=}1<br/>Xr:</big></code><br/>


The following represents more <u>condensed</u> ''':for ... :endfor''' control structure in a user-function than if it were shown in four separate lines:<br><font color=purple><strong>
<code>
A←1 3 5 7 ⋄ :for ii :in ⍳⍴A ⋄ A[ii]←A[ii]*2 ⋄ :endfor  ⍝Easier to maintain code if segmented well, esp. when surrounded by long code blocks.
</code></strong></font>


{{Article footer}}
{{Article footer}}
{{Symbol footer|11|D}}
{{Symbol footer|11|D}}

Latest revision as of 22:03, 21 February 2015

⋄ — Statement separator — Keystroke ALT+` (Accent grave) — Character 8900 or x22C4

[[file:]]
[[File:{{{kb2}}}]]

Usage

While the diamond operator (⋄) can be used in an immediate statement to the Session Manager, it is most commonly used in a function to start a new statement on the same physical line-row of user-code. It is used similarly to the semi colon (;) in C, Pascal, PHP and many other languages, or the colon (:) and backslash (\) in some versions of Basic. It allows another statement to be concisely set on the same line.

Note: The ⋄ operator cannot be used after a lamp (⍝) comment operator appears on the same line, as all characters after ⍝ are ignored.

Also note the ⋄ operator represents an exception to the rule that APL's interpreter executes from right to left, since the leftmost APL statement is executed BEFORE the adjacent APL statement after the next ⋄ operator and so on. Each APL statement is executed sequentially as if listed on multiple lines. The ⋄ operator also helps condense APL code since fewer visual lines will contain the same amount of APL coding - and in many instances it can result in cleaner, or easier-to-read-and-understand APL code.

Examples

In the first example, the variable K is tested to see if it is greater than or equal to 1. If the test fails, k is set to 1.

→(k≥1)/Xr ⋄ K←1
Xr:     ⍝This branch/goto Label is deliberately placed first on its own line!

It is the same as

→(k≥1)/Xr
K←1
Xr:

The following represents more condensed :for ... :endfor control structure in a user-function than if it were shown in four separate lines:
A←1 3 5 7 ⋄ :for ii :in ⍳⍴A ⋄ A[ii]←A[ii]*2 ⋄ :endfor ⍝Easier to maintain code if segmented well, esp. when surrounded by long code blocks.


See Also
System Commands System Variables and Functions Operators


Keyboard
Alt+Shift ⍪ ≡ ≢ ⍒ ⍋ ⌽ ⍉ ⊖ ⍟ ⍱ ⍲ ⍠ ⌹
Alt ⋄ ¨ ¯ < ≤ ∅ ≥ > ≠ ∨ ∧ × ÷
Shift ~ ! @ # $ % ^ & * ( ) _ +
Key ` 1 2 3 4 5 6 7 8 9 0 - =
Alt+Shift ⍷ √ ⍨ ⍸ ⍥ ⍣ ⍞ ⍬ ⊣
Alt ? ⍵ ∊ ⍴ § ↑ ↓ ⍳ ○ π ← → ⊢
Shift Q W E R T Y U I O P { } |
Key q w e r t y u i o p [ ] \
Alt+Shift ∫ ∂ ⌻ ⍢ ⍙ ⍤ ⍫ ⌷
Alt ⍺ ⌈ ⌊ ∞ ∇ ∆ ∘ ‼ ⎕ ⍎ ⍕
Shift A S D F G H J K L : "
Key a s d f g h j k l ; '
Alt+Shift ⊆ ⊇ χ ⍡ ⍭ ⊙
Alt ⊂ ⊃ ∩ ∪ ⊥ ⊤ ⍦ ⍝ ⍀ ⌿
Shift Z X C V B N M < > ?
Key z x c v b n m , . /
NARS 2000 Lang
Tool
Bar 		← → + - × ÷ * ⍟ ⌹ ○ ! ? √ | ⌈ ⌊ ⊥ ⊤ ⊣ ⊢
≡ ≢ < ≤ = ≥ > ≠ ∨ ∧ ⍱ ⍲ ↑ ↓ ⊂ ⊃ ⌷ ⍋ ⍒
⍳ ∊ ⍸ ⍷ ∪ ∩ ⊆ ⊇ ~ § π .. , ⍪ ⍴ ⌽ ⊖ ⍉
/ \ ⌿ ⍀ ⊙ ¨ ⍨ ⍤ ⍣ ⍡ ⍥ ⍦ . ∘ ⍠ ‼ ⌻ ∂ ∫ ⍞ ⎕ ⍎ ⍕
⋄ ⍝ ∇ ∆ ⍙ _ ⍺ ⍵ ¯ ⍬ ∞ ∅
Second Row i j k i j k l g p r v x

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