Branch: Difference between revisions
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(Created page with "{{Built-in|Branch|→}} is a primitive monadic function which provides a way to control execution flow in an APL programs. It is equivalent to GOTO...") |
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<source lang=apl> | <source lang=apl> | ||
⍝ While-Do construct | ⍝ While-Do construct | ||
While:→(~B)/Done | While: →(~B)/Done | ||
S1 | S1 | ||
→While | →While | ||
| Line 35: | Line 35: | ||
<source lang=apl> | <source lang=apl> | ||
⍝ Repeat-Until construct | ⍝ Repeat-Until construct | ||
Repeat:S2 | Repeat: S2 | ||
→(~B)/Repeat | →(~B)/Repeat | ||
</source> | </source> | ||
Note that <source inline lang=apl>Else</source>, <source inline lang=apl>End</source>, <source inline lang=apl>CaseN</source>, <source inline lang=apl>Next</source>, <source inline lang=apl>While</source>, <source inline lang=apl>Done</source>, <source inline lang=apl>Repeat</source> in the examples above are all user-defined labels rather than keywords. | |||
==External links== | ==External links== | ||
Revision as of 06:53, 27 July 2020
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Branch (→) is a primitive monadic function which provides a way to control execution flow in an APL programs. It is equivalent to GOTO statement in other programming languages.
It appeared in early versions of APL. In some APL dialects it was superseded by the more modern control structures.
Examples
Branch function can be used to implement structured programming constructs without the use of special keywords:[1]
⍝ If-Then-Else construct
→(~B)/Else
S1
→End
Else:
S2
End:
⍝ Select construct
→(Case1, Case2, Case3, Case4)[i]
Case1: S1
→Next
Case2: S2
→Next
Case3: S3
→Next
Case4: S4
Next:
⍝ While-Do construct
While: →(~B)/Done
S1
→While
Done:
⍝ Repeat-Until construct
Repeat: S2
→(~B)/Repeat
Note that Else, End, CaseN, Next, While, Done, Repeat in the examples above are all user-defined labels rather than keywords.
External links
Tutorials
- Bernard Legrand. Mastering Dyalog APL (page 208). Dyalog Ltd. November 2009.