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u :: v u :: n Adverse Conjunction
Rank Infinity -- operates on [x and] y as a whole -- WHY IS THIS IMPORTANT?
Provides an alternative verb v to be run if the verb u fails
If the right operand of :: is a noun n, it is equivalent to the constant verb (n"_) which ignores its arguments and produces the result n.
(+/ % #) :: 'bad data' i.8 NB. average the integers 0 to 7 inclusive 3.5 (+/ % #) :: 'bad data' 'string' NB. cannot add characters this way. bad data
Whitespace must separate verbA from ::
Otherwise J thinks the :: inflects verbA:: .
verbA:: verbB |spelling error | verbA:: verbB | ^ verbA :: verbB verbA ::verbB (+/ % #):: ('bad data'"_) i.8 |spelling error | (+/ % #):: ('bad data'"_) i.8 | ^
1. Adverse can simplify opening a file or database for append access
Open :: Create filename
2. Default ;:y to y in the case that noun y causes an error with (;:).
Used e.g. in: erase (~system/main/stdlib.ijs) and coinsert (~system/main/colib.ijs).-~
erase and coinsert are
- Standard Library word(s) residing in the 'z'-locale
- Defined in the factory script stdlib.ijs which is located in ~system/main/stdlib.ijs
- View the definition(s) in a JQt session by entering: open '~system/main/stdlib.ijs'
;: '''alpha' |open quote | 'alpha | ^ | ;:'''alpha' (;: :: ]) '''alpha' 'alpha
3. Close existing form (no longer needed), or continue (without error) if no existing form is present
wd :: 0: 'psel fm; pclose'
wd (the standard GUI interface) is a cover verb for the Foreign (11!:0) in J6.02
1. Debugging is turned off (including stops) during the execution of u.