Control structure: Difference between revisions
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For example, a function implementing the [[wikipedia:TPK algorithm|Trabb Pardo–Knuth algorithm]] using control structures: | For example, a function implementing the [[wikipedia:TPK algorithm|Trabb Pardo–Knuth algorithm]] using control structures: | ||
<source lang=apl> | <source lang=apl> | ||
∇ {res}←trabb | ∇ {res}←trabb;f;S;i;a;y | ||
f←{(0.5*⍨|⍵)+5×⍵*3} | f←{(0.5*⍨|⍵)+5×⍵*3} | ||
S←,⍎{⍞←⍵ ⋄ (≢⍵)↓⍞}'Please, enter 11 numbers: ' | S←,⍎{⍞←⍵ ⋄ (≢⍵)↓⍞}'Please, enter 11 numbers: ' | ||
Revision as of 09:34, 19 July 2020
Some modern versions of APL include a set of keywords for controlling the flow of control. 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.