Common lisp: is there a less painful way to input math expressions?
common-lisp, infix-notation, prefix, reader-macro, s-expression
Solution
There are reader macros for this purpose.
See: http://www.cliki.net/infix
For example:
CL-USER 17 > '#I(a*(8*b^^2+1)+ 4*b*c*(4*b^^2+1) )
(+ (* A (+ (* 8 (EXPT B 2)) 1)) (* 4 B C (+ (* 4 (EXPT B 2)) 1)))
`'` is the usual quote. `#I( some-infix-expression )` is the reader macro.
Problem
I enjoy common lisp, but sometimes it is really painful to input simple math expressions like ``` a(8b^2+1)+4bc(4b^2+1) ``` (Sure I can convert this, but it is kind of slow, I write (+ () ()) first, and then in each bracket I put (* () ())...) I'm wondering if anyone here knows a better way to input this. I was thinking about writing a math macro, where ``` (math “a(8b^2+1)+4bc(4b^2+1)”) ``` expands to ``` (+ (* a (1+ (* 8 b b))) (* 4 b c (1+ (* 4 b b)))) ``` but parsing is a problem for variables whose names are long. Anybody has better suggestions?