[Haskell-beginners] Re: How to import the Data.Char library in Hugs?

On Fri, 18 Sep 2009 04:52:17 +0200, Daniel Fischer wrote:

Am Freitag 18 September 2009 04:27:31 schrieb Benjamin L.Russell:

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On Thu, 17 Sep 2009 15:04:07 +0200, Daniel Fischer

wrote:

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Am Donnerstag 17 September 2009 14:41:47 schrieb Benjamin L.Russell:

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My apologies if this is an extremely elementary question, but I am having difficulties in importing the Data.Char library in Hugs.

Hugs> :a Data.Char Data.Char>

Thank you; that was exactly the information for which I was looking.

Incidentally, what option name does 'a' represent? That one doesn't appear when I type ":?." Shouldn't it appear in that list?

It should, and it does for me (hugs september 2006):

Hugs> :? LIST OF COMMANDS: Any command may be abbreviated to :c where c is the first character in the full name.

:load <filenames> load modules from specified files :load clear all files except prelude :also <filenames> read additional modules <--- There :reload repeat last load command

Oops; you're right: The structure of the two commands above it was the following:

:load <filenames> load modules from specified files :load clear all files except prelude

Apparently, for some reason, when I tried to scan through the list, I subconsciously grouped the two commands below similarly:

:also <filenames> read additional modules :reload repeat last load command

Therefore, I somehow only read the second line of what I thought was a structurally similar second group, and therefore noticed the ":reload," but not the ":also," expecting the command above it to be ":reload <filenames>." I probably should have either read more slowly (I was rushing out to lunch at the time), or somehow avoided unconsciously assuming patterns that didn't exist. Too much mental pattern-matching ;-).

Unfortunately, Hugs' behaviour is much less convenient than ghci's:

Hugs> :also Data.Char SimplTest SimplTest> ord 'a' ERROR - Undefined variable "ord" SimplTest> Data.Char.ord 'a' ERROR - Undefined qualified variable "Data.Char.ord"

You can't directly use it, neither qualified nor unqualified, you have to switch contexts with :m(odule):

SimplTest> :m Data.Char Data.Char> ord 'a' 97 Data.Char> :m SimplTest SimplTest> filter (test 4) $ digl 3 [[0,0,0],[0,1,4],[0,2,8],[1,4,0],[1,5,4],[1,6,8],[2,8,0],[2,9,4]]

Interesting; what happens if I then need to use a higher-order function composed of other functions, some of which are from different modules, interactively? -- Benjamin L. Russell -- Benjamin L. Russell / DekuDekuplex at Yahoo dot com http://dekudekuplex.wordpress.com/ Translator/Interpreter / Mobile: +011 81 80-3603-6725 "Furuike ya, kawazu tobikomu mizu no oto." -- Matsuo Basho^