2012/2/29 ashok bakthavathsalam <lifebala...@gmail.com> > I am looking for something similar to > ToExpression<http://reference.wolfram.com/mathematica/ref/ToExpression.html> > that > is available in Mathematica. I just want to convert a string to an > expression, and evaluate the expression. As a first pass, my strings will > include only numbers and arithmetic operators, and not even parentheses. > > If I need to write it, please point me in the direction of the appropriate > pre-defined modules/definitions which I should use. >
Maybe you can use this parser for infix expressions. http://planet.racket-lang.org/package-source/soegaard/infix.plt/1/0/planet-docs/manual/index.html Here is a small example (it takes a while for the library to install - it seems it old Schematics test suite takes forever to install these days - I need to switch to a builtin one). #lang at-exp racket (require (planet soegaard/infix) (planet soegaard/infix/parser)) (display (format "1+2*3 is ~a\n" @${1+2*3} )) (parse-expression #'here (open-input-string "1+2*3")) The output will be: 1+2*3 is 7 .#<syntax:6:21 (#%infix (+ 1 (* 2 3)))> The function parse-expression parses the expression in the string and returns a syntax-object that resembles the output of ToExpression. -- Jens Axel Søgaard
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