- Haskell-Cafe - Haskell.org

Infix expressions
by Ken Shan 29 Jul '02

29 Jul '02

Hello, In Haskell, backquotes can be used to convert individual identifiers into infix operators, but not complex expressions. For example, [1,2,3] `zip` [4,5,6] is OK, but not [1,2,3] `zipWith (+)` [4,5,6] Is there any reason other than potential confusion when one of the two backquotes is accidentally omitted? In any case, perhaps some people on this mailing list would appreciate the following implementation of "infix expressions" that Dylan Thurston and I came up with -- as algebraic and perverse as we could manage: infixr 0 -:, :- data Infix f y = f :- y x -:f:- y = x `f` y main = print $ [1,2,3] -: zipWith (+) :- [4,5,6] -- Edit this signature at http://www.digitas.harvard.edu/cgi-bin/ken/sig The trick is that there is no trick.

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Haskell is more known than we might think
by oleg＠pobox.com 29 Jul '02

29 Jul '02

Hello! The other day I received, among other junk mail, coupons for the local 7-eleven store. I subconsciously scanned the envelope, and almost jumped when I read the return address: 7-Eleven, Inc. 2711 North Haskell Avenue Dallas, TX 75204 It seems a rather long Avenue (with at least 27 blocks); presumably it has the Southern part too. Being associated with the most successful worldwide convenience store chain bodes well for the language.

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(no subject)
by Scott J. 28 Jul '02

28 Jul '02

I think I am in the wrong pub. It seems I am alone here. Scott

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Uluslararas� �� FIRSATI..
by �� F�rsat� 28 Jul '02

28 Jul '02

Uluslararası amerikan firması sağlık, kozmetik, gıda ve telekomünikasyon alanında uluslar arası çalışma imkanı tanıyor. Önkoşulsuz, sermayesiz ve risksiz. Dilerseniz ek gelir dilerseniz milyon $ 'lık bir iş; .......ve bağımsız! İlgileniyorsanız. Selim Bengi. Ofis Tel: 0312 232 33 81 pbx. GSM : 0546 265 06 10 : 0542 516 27 65 e-mail: vizyonlife(a)mynet.com

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converting capital letters into small letters
by Karen Y 27 Jul '02

27 Jul '02

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Doubts...
by Pedro L. P. Dias 27 Jul '02

27 Jul '02

Dear Professor: My name is Carlos Alexandre Grimaldi. I'm engineering student at Federal University of Rio de Janeiro, Brazil. I began my studies in Haskell, and I have some doubts which I report here. I'm very gratefully if you could help me. I'm following a book I downloaded from Internet: "A Gentle Introduction to Haskell, Version 98". Following this, I face some problems: - "inc :: Integer -> Integer" don't work - "inc n = n+1" don't work too; - "data Bool = False | True" also...; - "data Color = Red | Green | Blue | Indigo | Violet" also fails. I thought that this commands and definitions must be inside a program, and don't at prompt "prelude>". So, I opened other book, also downloaded from Internet: "The Hugs 98 User Manual", and I tryed: "module Fact where fact :: Integer -> Integer fact n = product [1..n]" thinking that would be created a file "Fact", in which the definitions for "fact" would work. But this also yield an error... So, I ask you: - is necessary the creation of a file where that definitions could work? - is this file a ".hs"? - how can I create a file like this? Which command or editor? - or, if I wrong, why that examples don't work? Thank you very much for your help. Best regards, Carlos A. Grimaldi.

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RE: converting capital letters into small letters
by Garner, Robin 26 Jul '02

26 Jul '02

> 1. How would I convert capital letters into small letters? > > 2. How would I remove vowels from a string? I expect the first problem is actually to convert the upper case letters in a string to lower case, as the single-character version isn't a very interesting problem. A little thought shows that the first problem can be expressed as both a catamorphism or an anamorphism. The anamorphic solution would be [(p,f)] where p as = as == [] and f (a:as) = (makeLowerCase a, bs). The solution to the second problem is clearly a catamorphism, and one solution might be (|[],g|) where g (a:as) = if isVowel a then as else a:as The definitions of 'makeLowerCase' and 'isVowel' are quite simple (assuming English/Ascii, as pointed out in other messages), while finding the prelude functions for the patterns of recursion might take a little more thought. Suitable, possible, as homework questions in an introductory Haskell course ... Robin

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Re: converting capital letters into small letters
by Ashley Yakeley 26 Jul '02

26 Jul '02

At 2002-07-25 19:07, Andrew J Bromage wrote: >> 1. How would I convert capital letters into small letters? >> 2. How would I remove vowels from a string? > >As you've probably found out, these are very hard problems. The build process of my HBase project automatically downloads the official data files from the Unicode web-site and automatically converts them into useful Haskell functions by the miracle of m4 -- including this one: toUpperCase :: Char -> Char; I also have the names for all the characters, because hard-drive space is cheap: getCharacterName :: Char -> String; ...and many other useful normative and informative character properties, such as general category, etc. See <http://sourceforge.net/projects/hbase/>. Mind you it's in a bit of an odd state right now. As for vowels, I'm pretty sure Unicode has nothing to say on the subject, as different languages may share the same characters but have different ideas as to what is and what isn't a vowel. -- Ashley Yakeley, Seattle WA

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Uluslararas� �� FIRSATI..
by �� F�rsat� 25 Jul '02

25 Jul '02

Uluslararası amerikan firması sağlık, kozmetik, gıda ve telekomünikasyon alanında uluslar arası çalışma imkanı tanıyor. Önkoşulsuz, sermayesiz ve risksiz. Dilerseniz ek gelir dilerseniz milyon $ 'lık bir iş; .......ve bağımsız! İlgileniyorsanız. AYLA HAYBAT wayscanada(a)hotmail.com Ayrıntılı Bilgi: www.herbalife.com ---------------------------------------------------------------------------------------------------------------------------- AMERİKA GREEN CARD GÖÇMENLİK ÇEKİLİŞİ KANADA GÖÇMENLİĞİ İNGİLTERE DE ÜCRETSİZ ingilizce EĞİTİM..... BİLGİ İÇİN www.myvizyon.com u ziyaret ediniz....

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Size �zell....
by seni＠istiyorum.com 24 Jul '02

24 Jul '02

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