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{{Built-in|Branch|→}} is a [[Primitive function|primitive]] [[monadic function]] which provides a way to control execution flow in an APL | {{Built-in|Branch|→}} is a [[Primitive function|primitive]] [[monadic function]] which provides a way to control execution flow in an APL program. 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 In some APL dialects it was superseded by the more modern [[control structure]]s. | It appeared in early versions of APL. In some APL dialects it was superseded by the more modern [[control structure]]s. | ||
Revision as of 07:37, 27 July 2020
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Branch (→) is a primitive monadic function which provides a way to control execution flow in an APL program. 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 In some APL dialects it was superseded by the more modern control structures.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.