Yet another useful little function is Twiddle, which takes in
a function and reverses the order that function takes its (first two)
arguments.
Again, there aren't many immediate uses for such a function, but it'll
come in handy later on. It satisfies the properties
#math97#
| Twiddle~First |
= |
Second |
|
| Twiddle~Second |
= |
First |
|
| Compose~Twiddle~Twiddle |
= |
Identity |
|
Its TEX equivalent is
This function is called ``twiddle'' because it is sometimes written
#math98##tex2html_wrap_inline2170# (and ∼ is pronounced ``twiddle'').
It also twiddles its arguments around,
which is quite nice if your sense of humour runs to appalling puns.