generalized stack operators

stevan apter — 2000-06-27 11:30:54

in conk, i've defined



dup == 1 ndup;

pop == 1 npop;

dip == 1 ndip;

ary == 1 nary;

app == 1 napp;

choice == 2 nchoice;

swap == 1 2 nmswap;



where the parameterized versions are primitive:



ndip        [P] N -> R   

R is P applied to Nth item down.

      

nary        [P] N -> R   

executes P, but no matter how many parameters this consumes, N are removed from the stack. 



napp        .. XN [P] N -> R1 ..  

executes P N times, with .. XN on top of the stack.  Returns N values R1 .. . 



npop        N -> R    

removes N items from the top of the stack.



ndup        X N -> R   

makes N copies of the top of the stack.



nmrot        N M -> R   

M-rotate the top N items of the stack.



nmswap       N M -> R   

swap N-th and M-th items down on the stack.



nlist        N -> X    

X is a list of the top N items.



nchoice      I .. XN N -> Xi   

Xi is the I-th item of the top N items on the stack.



particularly in the case of ary and app, this seemed more economical than having primitives

app1, app2, app3, nullary, binary, ternary, etc.



partly, it was a matter of trying to confine this family of operations to a small set.



any ideas on the best way to proceed here?