interestingly enough this is ok:
foo ← {⍬{⍺,(1+1↑⍵),(foo 1↓⍵)}⍣(~0=⍴⍵)⍵}
foo 1 2 3
2 3 4
but this isnt:
foo ← {⍺{⍺,(1+1↑⍵),(foo 1↓⍵)}⍣(~0=⍴⍵)⍵}
⍬ foo 1 2 3
VALUE ERROR
foo[1] λ←⍺ λ1⍣(∼0=⍴⍵)⍵
^
⎕CR 'foo'
λ←⍺ λ1 ⍵
λ←⍺{⍺,(1+1↑⍵),(foo 1↓⍵)}⍣(~0=⍴⍵)⍵
On Wed, Oct 9, 2019 at 1:29 PM Rowan Cannaday <cannad...@gmail.com> wrote:
> making progress...
>
> foo ← {{(1+1↑⍵),(foo 1↓⍵)}⍣(~0=⍴⍵)⍵}
> foo 1 2 3
> 2 3 4
>
> On Wed, Oct 9, 2019 at 12:47 PM Rowan Cannaday <cannad...@gmail.com>
> wrote:
>
>> this is a slightly better way of writing my (still broken) accumulator:
>> acc←{⍺{⍺ acc 1↑⍵}⍣(0=⍴⍵)⊢⍵}
>>
>> On Wed, Oct 9, 2019 at 12:40 PM Rowan Cannaday <cannad...@gmail.com>
>> wrote:
>>
>>> Given a recursive factorial definition:
>>> fact←{{⍵ × fact ⍵-1}⍣(⍵>2)⊢1⌈⍵}
>>>
>>> [written by Kacper Gutowski in the 'Recursive Lambda' thread]
>>>
>>> I am attempting to write a basic accumulator. This should take an empty
>>> vector as the left value argument, and a rank 1 array as the right value
>>> argument.
>>> Every iteration it should drop a value from the right value, and append
>>> it to the left, until the right value is an empty vector.
>>>
>>> I thought I'd be able to do something like the following:
>>> acc←{⍺,{acc 1↑⍵}⍣(0=⍴⍵)⊢⍵}
>>> ⍬ acc 1 2 3
>>>
>>> But modifying this to say, add a 1 to every number, still returns the
>>> input vector ⍵.
>>>
>>> Thoughts?
>>>
>>>
>>> On Fri, Sep 27, 2019 at 3:44 PM Rowan Cannaday <cannad...@gmail.com>
>>> wrote:
>>>
>>>> Hello y'all.
>>>>
>>>> I have been attempting to learn function composition & higher-order
>>>> functions in gnu-apl, and how to use it to perform tree traversal.
>>>>
>>>>
>>>> https://en.wikipedia.org/wiki/Function_composition_(computer_science)#APL
>>>> https://en.wikipedia.org/wiki/Higher-order_function#APL
>>>> https://rosettacode.org/wiki/Tree_traversal#APL
>>>>
>>>> Unfortunately a lot of the syntax used is dyalog & dfn specific, so
>>>> working out some of the examples is a bit tricky for myself.
>>>> (the main inconsistencies are '∇' as a recursive function definition,
>>>> ⍺⍺ & ⍵⍵ to refer to left and right operands, '@' as the 'at' operator, '⍣'
>>>> operator differences, as well as possibly others).
>>>>
>>>> Has anybody done 'idiomatic' tree traversal in gnu-apl? Does anybody
>>>> use primitive composition functions in their code?
>>>>
>>>> Trying to figure out what works and feels natural in the language. Any
>>>> examples or guidance would be appreciated.
>>>>
>>>> Examples:
>>>>
>>>> Higher order fns in gnu-apl:
>>>> ∇Z ← (L twice) B
>>>> Z ← L L B
>>>> ∇
>>>>
>>>> ∇Z ← plusthree B
>>>> Z ← B + 3
>>>> ∇
>>>>
>>>> ∇Z ← g B
>>>> Z ← plusthree twice B
>>>> ∇
>>>>
>>>
