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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").
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").


As of 2020, dfns are fully implemented in [[Dyalog APL]], [[NARS2000]], [[ngn/apl]], [[dzaima/APL]], and partially in [[GNU APL]].
As of 2020, dfns are fully implemented in [[Dyalog APL]], [[NARS2000]], [[ngn/apl]], [[dzaima/APL]], and partially in [[GNU APL]].

Revision as of 12:33, 20 December 2019

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").

As of 2020, dfns are fully implemented in Dyalog APL, NARS2000, ngn/apl, dzaima/APL, and partially in GNU APL.

Wikipedia has a full treatment of dfns.

Documentation

External links

APL syntax [edit]
General Comparison with traditional mathematicsPrecedenceTacit programming (Train, Hook, Split composition)
Array Numeric literalStringStrand notationObject literalArray notation (design considerations)
Function ArgumentFunction valenceDerived functionDerived operatorNiladic functionMonadic functionDyadic functionAmbivalent functionDefined function (traditional)DfnFunction train
Operator OperandOperator valenceTradopDopDerived operator
Assignment MultipleIndexedSelectiveModified
Other Function axisBracket indexingBranchStatement separatorQuad nameSystem commandUser commandKeywordDot notationFunction-operator overloadingControl structure