On Thu, Apr 28, 2005 at 09:22:15PM -0400, Cale Gibbard wrote:
The second problem arises from hugs not doing the same thing as ghci with respect to looking up qualified variable names (that is, those with the module name specified, in this case, the standard module Char). You can tell hugs to also load the Char module on top of whatever code you have loaded by using the command ":also Char", after which the prompt should look like Char> and you can try toUpper 'a'
Might as well use :load -- in both case Char becomes the new current module, making the old current module inaccessible. Hal: Char.toUpper and Char.isLower in Chapter 3 seem to be a perennial stumbling block for Hugs users -- could you suggest that Hugs users load Char and just say toUpper and isLower instead?
(without the Char, hugs doesn't seem to like qualified names, perhaps someone else can explain this)
Since you ask: the names in scope at the Hugs prompt are exactly those in scope inside the current module, which is Char in this case. Now Char just imports and re-exports names from Data.Char, so inside Char there is no Char.toUpper, just toUpper and Data.Char.toUpper. On the other hand, inside a module Test that imports Char, you can refer to Char.toUpper as well as toUpper.