The _tuple function takes one argument and makes a one element tuple. Note that the main Felix programming language does not allow one element tuples. The macro processor does though.
The _tuple_cons function takes two arguments, an element and a tuple, and constructs a single tuple starting with the first argument followed by the elements of the second argument: this is the usual list cons function of functional programming languages.
These two functions are most useful in recursive expansions, particularly when driven by user defined nontermial parses (see the next section).
1: #line 663 "./lpsrc/flx_tut_macro.pak" 2: #include <flx.flxh> 3: macro var x = _tuple 1; 4: macro x = _tuple_cons (2,x); 5: macro x = _tuple_cons (3,x); 6: macro for val i in x do print i; print " "; done; endl; 7: