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Foreign !:
J interfaces with the environment are provided by the conjunction!: (foreign). In most cases the foreign result is a verb that provides a specific service. The left argument of foreign selects a general family of services and the right argument selects a specific service. The families of services selected by the left argument are:
0 scripts
1 files
2 host commands
3 types
4 names
5 representations
6 time
7 space
9 global parameters
11 windows
13 debug
15 dynamic link library (shared library)
18 locales
128 numerical functions
The foreign conjunction is documented in the J Dictionary.
You have run across a few specific uses of the foreign conjunction in earlier sections.
The derived verb 9!:11 was used in the Print precision section. The 9 selects the global parameters family and the 11 gives a derived verb that sets the print precision.
The load verb uses 0!:0 to load scripts. The left argument selects the scripts family. Look up the definition. The 0 right argument is treated as three decimal digits 000 and therefore executes sentences from a file, stops on an error, and is silent (does not display sentences or results).
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