mappkg.spad line 58 [edit on github]
various Currying operations.
f^n is the function which is the n-fold application of f.
coerce A changes its argument into a nullary function.
id x is x.
nullary A changes its argument into a nullary function.
recur(g) is the function h such that h(n, x)= g(n, g(n-1, ..g(1, x)..)).