Doubts...
Pedro L. P. Dias
pedrolpd@uol.com.br
Fri, 26 Jul 2002 22:50:58 -0300
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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 =3D n+1" don't work too;
- "data Bool =3D False | True" also...;
- "data Color =3D 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 =3D 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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<STYLE></STYLE>
</HEAD>
<BODY bgColor=3D#ffffff>
<DIV>
<DIV>
<DIV>Dear Professor:</DIV>
<DIV> </DIV>
<DIV>My name is Carlos Alexandre Grimaldi. I'm engineering student =
at=20
Federal University of Rio de Janeiro, Brazil. I began my studies =
in=20
Haskell, and I have some doubts which I report here.</DIV>
<DIV>I'm very gratefully if you could help me.</DIV>
<DIV>I'm following a book I downloaded from Internet: "A Gentle =
Introduction to=20
Haskell, Version 98". Following this, I face some problems:</DIV>
<DIV> </DIV>
<DIV>- "inc :: Integer -> Integer" don't work</DIV>
<DIV> </DIV>
<DIV>- "inc n =3D n+1" don't work too;</DIV>
<DIV> </DIV>
<DIV>- "data Bool =3D False | True" also...;</DIV>
<DIV> </DIV>
<DIV>- "data Color =3D Red | Green | Blue | Indigo | Violet" also =
fails.</DIV>
<DIV> </DIV>
<DIV>I thought that this commands and definitions must be inside a =
program, and=20
don't at prompt "prelude>". So, I opened other book, also =
downloaded=20
from Internet: "The Hugs 98 User Manual", and I tryed:</DIV>
<DIV> </DIV>
<DIV>"module Fact where</DIV>
<DIV>fact :: Integer -> Integer</DIV>
<DIV>fact n =3D product [1..n]"</DIV>
<DIV> </DIV>
<DIV>thinking that would be created a file "Fact", in which the =
definitions for=20
"fact" would work. But this also yield an error... So, I ask =
you:</DIV>
<DIV> </DIV>
<DIV>- is necessary the creation of a file where that definitions could=20
work?</DIV>
<DIV> </DIV>
<DIV>- is this file a ".hs"?</DIV>
<DIV> </DIV>
<DIV>- how can I create a file like this? Which command or =
editor?</DIV>
<DIV> </DIV>
<DIV>- or, if I wrong, why that examples don't work?</DIV>
<DIV> </DIV>
<DIV>Thank you very much for your help.</DIV>
<DIV>Best regards,</DIV>
<DIV>Carlos A. Grimaldi.</DIV></DIV></DIV></BODY></HTML>
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