* On Thursday, June 19 2008, Ketil Malde wrote:

As a side note, may I advise you to use another symbol, and leave the poor dot alone? Overloading it as a module separator is bad enough. If you have a keyboard that allows greater-than-ascii input, there are plenty of options: « » ¡ £ ¥ ł € ® ª...

And even if you have a plain us layout in hardware, you can use us-international layout (or whatever it is called). So we can make haskell sort of like apl... While we are kind of on this topic, what makes the characters ħ þ prefix operator by default, while º and most other odd ones infix?

"Albert Y. C. Lai" writes:

...

While we are kind of on this topic, what makes the characters ħ þ prefix operator by default, while º and most other odd ones infix?

alphanumeric vs non-alphanumeric

Testing this, I find that isAlpha is True also for 'º', but as the OP claims, Haskell will use it as a(n infix) symbol. Neither does isSymbol (all False), isLetter (all True), isMark (False), nor isPunctuation (Fals) help to separate these. The HR defines uniSymbol -> any Unicode symbol or punctuation but I couldn't find any clear way to identify of these. -k -- If I haven't seen further, it is by standing in the footprints of giants

After some fiddling with this style, here is what I came up with for the 8 queens problem in the 99 problem set. It's quite entertaining ... ( note: it's brute force and requires a combination library ) queens2 n = n.permutations.filter all_satisfied where all_satisfied queens = queens.diff_col && queens.diff_diag diff_col queens = queens.unique.is queens diff_diag queens = n .combinations 2 .map (map (subtract 1)) .map (id &&& flip cherry_pick queens) .any same_dist.not where same_dist (row_pair, col_pair) = row_pair.foldl1 (-).abs == col_pair.foldl1 (-).abs -- generic helper cherry_pick ids xs = ids.map (xs !!) is a b = a == b unique xs = nub xs Guess this can conclude this experiment :) jinjing On Sun, Jun 22, 2008 at 1:10 AM, Ian Lynagh wrote:

On Fri, Jun 20, 2008 at 07:57:58AM +0200, Ketil Malde wrote:

...

"Albert Y. C. Lai" writes:

...

...

While we are kind of on this topic, what makes the characters ħ þ prefix operator by default, while º and most other odd ones infix?

...

alphanumeric vs non-alphanumeric

Testing this, I find that isAlpha is True also for 'º', but as the OP claims, Haskell will use it as a(n infix) symbol.

This is a bug in GHC. The characters <= '\255' were done specially, but incorrectly for many of those >= '\128'. I'll fix it, probably by just removing the specialisation for them.

Thanks Ian

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On Thu, 2008-06-19 at 15:24 -0400, Brent Yorgey wrote:

On Thu, Jun 19, 2008 at 3:35 AM, Ketil Malde wrote: jinjing writes:

> Any way here's the code:

> module Dot where > import Prelude hiding ( (.) )

> (.) :: a -> (a -> b) -> b > a . f = f a

> infixl 9 .

Isn't this (roughly?) the same as flip ($)?

As a side note, may I advise you to use another symbol, and leave the poor dot alone? Overloading it as a module separator is bad enough. If you have a keyboard that allows greater-than-ascii input, there are plenty of options: « » ¡ £ ¥ ł € ® ª...

Note that there already is a standard symbol for this, (>>>) from Control.Arrow. Well, actually (>>>) is more general than backwards function composition, so maybe making your own symbol is still a good idea while you're learning.

Application, not composition. Cont's return would work if it weren't for the wrapping. Similarly, (>>=) for the Id monad.