Writing a simple expression evaluator calculator

Lots of new toys out there on the Internet lately. Seems like the web is the way to go, and every software spigot is demanding they be 'web-enabled'. A lot are reinventing the wheel, bundling sub-standard web servers to serve up their HTML and Java interface.

Writing a simple expression evaluator calculator

An assert macro with informative failure reports, as a syntax-rule or a defmacro. A concise definition form with optional arguments and default values MetaScheme, or untyped MetaOCaml and the underlying alpha-conversion macro Applicative syntax-rules: It is very difficult to write macros that compose, to assemble complex macros from already written and tested components.

The previous approaches to composable syntax-rules are heavy, notationally and computationally. This article presents an alternative, lightweight style of writing composable syntax-rules, based on the CK abstract machine.

We demonstrate recursive, higher-order applicative macros defined in the style that looks like that of ML or strict Haskell. We write composable, call-by-value--like macros without resorting to the continuation-passing-style and thus requiring no macro-level lambda.

The syntax remains direct-style, with nested applications. Syntax-rules are difficult to compose because of their evaluation order: That per se does not preclude functional composition since the normal-order lambda-calculus or non-strict languages like Haskell do not evaluate arguments of a function application either.

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However, lambda-calculus has first-class anonymous abstractions; Haskell also has the case form that forces evaluation of an expression, to the extent needed to choose among the pattern-match clauses.

Syntax-rules have none of these compensating features. Generally, a syntax-rule cannot obtain the result of the expansion of its argument expression. The article on Systematic Macro Programming on this page explains the composability problem in detail.

So far, the only way out has been to effectively change the evaluation order by writing macros in the continuation-passing style CPS. However, CPS code is hard to read.

Furthermore, building continuations requires the notation for first-class, preferably anonymous syntax-rule abstractions.

Scheme Macro Programming

Although the latter are possible to emulate, the result is stylistically ugly and computationally expensive. Some macro expanders take the shocking amount of time and memory to expand CPS macros with anonymous abstractions.

This project was inspired by the question posed by Dan Friedman in March Write the macro permute that takes any number of arguments and returns the list of their permutations: One should write permute without resorting to CPS.

Our answer is the transliteration of the standard Haskell code implementing the straightforward algorithm for all permutations: Our macros are written in a CK style.Simplify Expression Calculator.

A Tiny Expression Evaluator - CodeProject

This calculator will simplify fractions, polynomial, rational, radical, exponential, logarithmic, trigonometric, and hyperbolic expressions.

If you skip parentheses or a multiplication sign, type at least a whitespace, i.e. write sin x (or even better sin(x)) instead of sinx.

writing a simple expression evaluator calculator

This compilation is dedicated to the memory of our nameless forebears, who were the inventors of the pens and inks, paper and incunabula, glyphs and alphabets.

I think Modern Compiler Implementation in ML is the best introductory compiler writing text. There's a Java version and a C version too, either of which might be more accessible given your languages background. The book packs a lot of useful basic material (scanning and parsing, semantic analysis, activation records, instruction selection, RISC and x86 native code generation) and various.

Free logarithmic equation calculator - solve logarithmic equations step-by-step. How To Write A Calculator in 70 Python Lines, By Writing a Recursive-Descent Parser Feb 23/, Three months ago, I wrote a post detailing the process of writing a calculator using a parsing library.

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