Infpre - A Common Lisp infix utility
Infpre is a prefix <-> infix conversion tool
for Common Lisp. The intended use is for CL programs with long math formulas.
The package infpre contains:
- infix->prefix - function
- prefix->infix - function
- math - macro
- !! - macro
How does the infix->prefix function work?
infix->prefix takes two list arguments:
the expression and the operators. The expression
is just an ordinary lisp list and the operators are math symbols like + and *,
where list order gives presedence.
An important point is that the operators are not binary,
but list separators (like comma),
i.e. 1 + 2 + ... is a + separated list.
% (infix->prefix '(1 + 2 * 3 + 4) '(+ *))
(+ 1 (* 2 3) 4)
How does the prefix->infix function work?
Hopefully as expected.
How does the math macro work?
Works as defun, but with infix math. If name is _ then
it works as lambda.
% (math f (x)
(let ((a 0.1))
(exp (-1 * a * expt x 2))))
% (f 2)
How does the !! macro work?
It simply applies infix->prefix with standard math operators.
Since there are no read macroes there
must be spaces between the operators.
(!! (let ((a 42)) a - 2 * 2 * 10))
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