Dfn: Difference between revisions
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* Mastering Dyalog: [https://www.dyalog.com/uploads/documents/MasteringDyalogAPL.pdf#page=174 page 174] | * Mastering Dyalog: [https://www.dyalog.com/uploads/documents/MasteringDyalogAPL.pdf#page=174 page 174] | ||
=== Documentation === | === Documentation === | ||
* [ | * [https://help.dyalog.com/latest/#Language/Defined%20Functions%20and%20Operators/DynamicFunctions/Dynamic%20Functions%20and%20Operators.htm Dyalog] | ||
* [https://www.gnu.org/software/apl/apl.html#Section-3_002e7 GNU APL] | * [https://www.gnu.org/software/apl/apl.html#Section-3_002e7 GNU APL] | ||
{{APL syntax}}[[Category:Kinds of functions]][[Category:Defining functions]] | {{APL syntax}}[[Category:Kinds of functions]][[Category:Defining functions]] | ||
Revision as of 14:47, 14 July 2020
A dfn (contraction of direct function or dynamic function, pronounced "dee fun") is an alternative way to define a function and operator, invented by John Scholes. A dfn operator can also be called a dop (pronounced "dee op").
John Scholes was responsible for numerous presentations and publications on and about dfns, and until his passing he maintained the dfns website.
As of 2020, dfns are fully implemented in Dyalog APL, NARS2000, ngn/apl, dzaima/APL, and partially in GNU APL, although not all dialects implement lexical scoping, in contrast to the dynamic scoping of tradfns. In other words, a dfn cannot "see" locals of its caller, but can see locals of its definer.
Wikipedia includes a thorough treatment of dfns.
External links
Tutorials
- APL Cultivation: Diving Into Functions in APL
- Mastering Dyalog: page 174
Documentation