diff --git a/Hascal.hs b/Hascal.hs --- a/Hascal.hs +++ b/Hascal.hs @@ -1,67 +1,144 @@ --- |'Hascal' is both a simple but extendable calculator library for Haskell +-- |Hascal is both a simple but extendable calculator library for Haskell -- and a command-line program using it. -- -- Also, its source code is a nice example for a minimalistic Haskell project. +-- +-- Some examples for the usage of the command-line program: +-- +-- >>> hascal 1+2 +-- 3.0 +-- +-- >>> hascal 1+2*3-4/198^2 +-- 6.99989796959493929190898887868584838281807978777676 +-- +-- Also, preceding exclamation marks mean that the following number is +-- imaginary, that is, you have to multiply it with i. E.g.: +-- +-- >>> hascal _1 ^ 0.5 +-- !1.0 +-- +-- And as you can see, negative numbers are preceded by a underscore. +-- +-- Although hascal itself doesn't understand brackets, you can use your shell +-- to get that functionality, like this (using bash): +-- +-- >>> hascal e ^ $(hascal i*pi) +-- -1.0 +-- +-- Speaking of shells, you should consider that your shell might extend an +-- asterisk (*) to the files at the current directory, like here: +-- +-- >>> echo * +-- _darcs dist hascal.cabal Hascal.hs LICENSE Main.hs README.org Setup.hs +-- +-- That's why this might not work: +-- +-- >>> hascal 1 * 2 +-- Error. :( +-- +-- But you could do this instead: +-- +-- >>> hascal 1*2 +-- 2 +-- +-- Yeah, that's it. Hascal is really minimalistic. +-- And I'm not planning to extend it much. module Hascal ( + -- * Types + -- |Just re-exporting the 'Complex' data-type for simplicity and comfort. + Complex, -- * Functions -- ** Operators operators, -- ** Evaluators eval, - hascal + hascal, + -- ** Pretty Printers + prettyPrint ) where -import Control.Arrow (second) -import Data.Function (on) -import Data.Number.CReal +import Control.Arrow (second) +import Data.Complex (Complex(..)) +import Data.Functor ((<$>)) +import Data.List (find) + + -- |'operators' is the default list of operators. -- -- An operator consists of one character and a function with of type --- @CReal -> CReal -> CReal@. +-- @Number -> Number -> Number@. -- -- 'operators' includes: -- --- * addition, represented by @\'+\'@ +-- * addition, represented by @\'+\'@, -- --- * subtraction, represented by @\'-\'@ +-- * subtraction, represented by @\'-\'@, -- --- * multiplication, represented by @\'c\'@ +-- * multiplication, represented by @\'c\'@, -- --- * division, represented by @\'\/\'@ +-- * division, represented by @\'\/\'@, -- --- * exponentiation, represented by @\'^\'@ +-- * exponentiation, represented by @\'^\'@, and -- --- * logarithming (with flipped arguments, see below), represented by @\'?\'@ +-- * logarithming (with flipped arguments, see below), represented by @\'?\'@, -- -- such that these laws are held: -- -- > (a - b == c) == (a == b + c) -- > (a / b == c) == (a == b * c) -- > (a ? b == c) == (a == b ^ c) -operators :: [(Char, CReal -> CReal -> CReal)] +operators :: RealFloat t + => [(Char, Complex t -> Complex t -> Complex t)] operators = [ ('+', (+)) , ('-', (-)) , ('/', (/)) , ('*', (*)) , ('^', (**)) , ('?', flip logBase) - ]-- Respecting operator precedence, - -- you can add custom infix operators. + ] + -- |'eval' gets a list of operators and a string containing a mathematical -- expression/term which only uses those operators listed in the first -- argument, and returns the result of that term. -eval :: [(Char, CReal -> CReal -> CReal)] -> String -> CReal -eval [] a = read a -eval l@((c,f):s) a | z /= "" = on f (eval l.($m)) fst snd - | otherwise = eval s a - where m@(_,z) = second (drop 1) $ break (==c) a +eval :: (Read t, RealFloat t) + => [(Char, Complex t -> Complex t -> Complex t)] -- ^ list of operators + -> String -- ^ string containing term + -> Maybe (Complex t) -- ^ just result, or nothing +eval [] ('!':a) = ((0:+1)*) <$> findOrRead a +eval [] ('_':a) = negate <$> findOrRead a +eval [] a = findOrRead a +eval l@((c,f):s) a | z /= "" = case (eval l y,eval l z) of + (Just n,Just m) -> Just (f n m) + _ -> Nothing + | otherwise = eval s a + where (y,z) = second (drop 1) $ break (==c) a +findOrRead :: (Read t, Floating t) => String -> Maybe (Complex t) +findOrRead s = maybe (maybeRead s) (Just . fst) $ + find ((==s) . snd) [(pi:+0,"pi"),(exp 1:+0,"e"),(0:+1,"i")] + + +maybeRead :: (Read t, Num t) => String -> Maybe (Complex t) +maybeRead s | any (null . snd) (reads s :: [(Double,String)]) + = Just (read s:+0) + | otherwise + = Nothing + + -- |'hascal' is the default evaluator: -- --- > hascal = eval operators -hascal :: String -> CReal +-- @ hascal = 'eval' 'operators' @ +hascal :: (Read t, RealFloat t) => String -> Maybe (Complex t) hascal = eval operators + + +-- |'prettyPrint' prints a number nicely. +-- E.g., it doesn't show the real or imaginary part of the number if it's @0@. +prettyPrint :: (Show t, RealFloat t) => Complex t -> String +prettyPrint (r:+0) = show r +prettyPrint (0:+i) = '!' : show i +prettyPrint (r:+i) = show r ++ " + !" ++ show i diff --git a/Main.hs b/Main.hs --- a/Main.hs +++ b/Main.hs @@ -1,11 +1,12 @@ module Main where -import Control.Monad (liftM2, unless) -import Data.Number.CReal -import Hascal -import System.Environment (getArgs) +import Control.Monad +import Hascal +import System.Environment +import Data.Number.CReal main :: IO () main = getArgs >>= liftM2 unless null - (putStrLn . showCReal 80 . hascal . concat) + (putStrLn . maybe "Error. :(" prettyPrint . + (hascal :: String -> Maybe (Complex CReal)) . concat) diff --git a/hascal.cabal b/hascal.cabal --- a/hascal.cabal +++ b/hascal.cabal @@ -1,26 +1,30 @@ -name: hascal -version: 1.1 -synopsis: a minimal, extensible and precise calculator -description: Hascal is a minimal calculator with infix-operations - supporting addition, subtraction, division, multiplication, - exponentiation and logarithming. Brackets are not supported - yet. - Futhermore, it's easy to add custom operators. -stability: provisional -category: Math, Console, Tools, Utility, Utils, Parsing -homepage: https://github.com/MekeorMelire/hascal -bug-reports: https://github.com/MekeorMelire/hascal/issues -license: GPL -license-file: LICENSE -copyright: © 2012 Mekeor Melire -author: Mekeor Melire -maintainer: Mekeor Melire -tested-with: GHC ==7.0.4 -cabal-version: >= 1.6 -build-type: Simple +name: hascal +version: 1.3 +synopsis: A minimal, extensible and precise calculator +description: Hascal is a minimal calculator with infix-operations + supporting addition, subtraction, division, multiplication, + exponentiation and logarithming. + Futhermore, it's easy to add custom operators. +stability: provisional +category: Math, Console, Tools, Utility, Utils, Parsing +homepage: http://darcsden.com/mekeor/hascal +bug-reports: https://github.com/MekeorMelire/hascal/issues +license: GPL +license-file: LICENSE +copyright: 2012 Mekeor Melire +author: Mekeor Melire +maintainer: Mekeor Melire +tested-with: GHC ==7.0.4 +cabal-version: >= 1.6 +build-type: Simple source-repository head + type: darcs + location: http://darcsden.com/mekeor/hascal + + +source-repository head type: git location: git://github.com/MekeorMelire/hascal.git @@ -29,6 +33,7 @@ build-depends: base >2 && <5, numbers >= 3000 exposed-modules: Hascal ghc-options: -Wall + executable hascal build-depends: base >2 && <5, numbers >= 3000