The manual is here, see page 145: http://docs.dyalog.com/15.0/Dyalog%20APL%20Language%20Reference%20Guide.pdf
I'm not sure where Louis got the information about monadic G. I assure you that Dyalog APL does not examine G to see if it's monadic or dyadic. It always tries to apply G dyadically. Jay. On 15 August 2016 at 12:30, Juergen Sauermann <juergen.sauerm...@t-online.de > wrote: > Hi Jay, > > I see. Maybe I misunderstood Louis,s email from last Saturday completely? > The way I read this email was that in Dyalog APL version 15 you can have > a monadic condition function G in F⍣G . Quote from the email: > > > *The Dyalog 15.0 manual states that the power operator can take a* > *function right argument. In this case, that function can be* > *either monadic or dyadic, and can be a lambda.* > *If it’s monadic:* > > * (F⍣G) ⍵ ←→ ⍵ ← F ⍵ until G ⍵* > *⍺ (F⍣G) ⍵ ←→ ⍵ ← ⍺ F ⍵ until G ⍵* > > *If it’s dyadic:* > > * (F⍣G) ⍵ ←→ ⍵ ← F ⍵ until ( F ⍵) G ⍵* > *⍺ (F⍣G) ⍵ ←→ ⍵ ← ⍺ F ⍵ until (⍺ F ⍵) G ⍵* > > *(Note that G is checked before the first time F is executed.)* > > I don't know if that statement is correct or not, but if it is then I > would prefer to not > introduce this "monadic case" in GNU APL for the reasons explained earlier. > > Thanks, > Jürgen > > > On 08/15/2016 10:16 AM, Jay Foad wrote: > > On 13 August 2016 at 13:05, Juergen Sauermann < > juergen.sauerm...@t-online.de> wrote: > >> In "Mastering Dyalog APL" I haven't found the monadic case for the right >> function argument >> G of the power operator. In that book G seems to be always dyadic. So the >> monadic case looks >> like a new Dyalog invention. And, if it is defined like you say, IMHO not >> the ultimate wisdom. >> > > There is no "monadic case". G is always applied dyadically, and if it > happens to be a strictly monadic function then you'll get a SYNTAX ERROR: > > ⎕FX'r←g y' 'r←g>10' ⍝ g is strictly monadic > 2 g 4 ⍝ applying it dyadically gives an error > SYNTAX ERROR > (+⍨⍣g)1 ⍝ power operator tries to apply g dyadically > SYNTAX ERROR > > In general, Dyalog APL *never* examines a function operand to see whether > it is monadic or dyadic, in order to treat them differently. > > Jay. > > >
