I was browsing the APL2 documentation, and came
across the following code (page 56, on the
[0] Z←NAME GETW N
[1] ⍝ GET ITEMS N
FROM THE TABLE NAMED NAME
[2] Z←''
[3] →('NOT A VALID
TABLE NAME' ERR~(⊂NAME)∊TABLES)/0
[4] TAB←⍎NAME
[5] B←N∊TAB[;1]
[6]
→0ρ('ITEM(S)'((~B)/N)'NOT FOUND')ERR~^/B
[7] →(~∨/B)/0 ⍝ EXIT IF NONE
FOUND
[8] Z←(TAB[;1]∊N)⌿TAB
What is ERR
here? It seems like a function that sets some error state?
It certainly looks like something useful to have. I can't
think of any way I could build this myself though.