=. (Is (Local)) Noun/Other
Is (Local) =. is equivalent to Is (Global) =: unless it is part of an explicit definition (e.g. of a verb) in which case the value it assigns (which need not be a noun) holds good only whilst the verb is running.
On termination of the verb, the target of =. reverts to its former type and value.
'fe fi fo fum'=. i.4 fe ; fi ; fo ; fum +-+-+-+-+ |0|1|2|3| +-+-+-+-+ foo=: verb define fe=. 90 NB. holds true only while foo runs fi=. 91 NB. original values of fe and fi are not lost fo=: fe+fi NB. =: overwrites the original value of fo fum=. 1&+ NB. holds true only while foo runs (fum is now a verb) fum y ) foo 999 1000 NB. only fo has changed (as result of running: foo)... fe ; fi ; fo ; fum +-+-+---+-+ |0|1|181|3| +-+-+---+-+
Used where other languages would employ a local variable.