thereadme/mathexpr
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fix: negated number left as the last expression would fail

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Mahdi Dibaiee 2016-11-04 22:26:49 +03:30
parent 8b8c8b9d65
commit 2dbcd7c9eb
2 changed files with 2 additions and 1 deletions
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2
mathexpr.cabal
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@ -1,5 +1,5 @@
name: mathexpr name: mathexpr
version: 0.2.0.0 version: 0.2.0.1
synopsis: Parse and evaluate math expressions with variables and functions synopsis: Parse and evaluate math expressions with variables and functions
description: A simple tool to evaluate math expressions as strings with support for custom functions and operators description: A simple tool to evaluate math expressions as strings with support for custom functions and operators
homepage: https://github.com/mdibaiee/mathexpr homepage: https://github.com/mdibaiee/mathexpr

1
src/Data/MathExpr.hs
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@ -80,6 +80,7 @@ module Data.MathExpr
helper :: [String] -> [String] -> Double helper :: [String] -> [String] -> Double
-- negative numbers come in the form ["num", "-"] -- negative numbers come in the form ["num", "-"]
helper [] [o] = read o helper [] [o] = read o
helper [n, "-"] [] = negate . read $ n
helper (c:cs) os helper (c:cs) os
| c == "-" && length os < 2 = | c == "-" && length os < 2 =
let result :: Double = negate . read . head $ cs let result :: Double = negate . read . head $ cs