Control structure: Difference between revisions

Revision as of 11:24, 19 July 2020

Some modern versions of APL include a set of keywords for controlling flow of execution. Such keywords allow programmers to create control structures which are commonly used in procedural programming languages.

Example

Dyalog APL has a rich set of flow control keywords, including :If, :While, :Repeat, :For (with the supplementary control words :In and :InEach), :Select, :With, :Trap, :Hold and :Disposable. The use of control structures defined by these keywords is only allowed in defined functions.

For example, a function implementing the Trabb Pardo–Knuth algorithm using control structures:

∇ {res}←trabb;f;S;i;a;y
  f←{(0.5*⍨|⍵)+5×⍵*3}
  S←,⍎{⍞←⍵ ⋄ (≢⍵)↓⍞}'Please, enter 11 numbers: '
  :For i a :InEach (⌽⍳≢S)(⌽S)
      :If 400<y←f(a)
          ⎕←'Too large: ',⍕i
      :Else
          ⎕←i,y
      :EndIf
  :EndFor
∇

External links

Tutorials

APL Cultivation: Control structures
Bernard Legrand. Mastering Dyalog APL (page 189). Dyalog Ltd. November 2009.

Documentation

Dyalog
APLX

@@ Line 24: / Line 24: @@
 * Bernard Legrand. [https://www.dyalog.com/uploads/documents/MasteringDyalogAPL.pdf#page=189 Mastering Dyalog APL (page 189)]. [[Dyalog Ltd]]. November 2009.
 === Documentation ===
-* [https://help.dyalog.com/latest/#Language/Control%20Structures/Control%20Structures%20Introduction.htm#ControlStructures Dyalog – Control Structures]
+* [https://help.dyalog.com/latest/#Language/Control%20Structures/Control%20Structures%20Introduction.htm#ControlStructures Dyalog]
+* [http://microapl.com/apl_help/ch_020_010_047.htm APLX]
 [[Category:APL syntax]]