FLI types are defined for integers of particular sizes. These are equivalent to the types defined by ISO C99. For example, Lisp :int8
is ISO C99 int8_t.
The types have these meanings:
8-bit signed integer
16-bit signed integer
32-bit signed integer
64-bit signed integer
The largest type of signed integer available
A signed integer the same size as a pointer
LispWorks Foreign Language Interface User Guide and Reference Manual - 29 Sep 2017