fastest way to turn the string s to its value is ". s
You may get an error if it's ill-formatted. Henry Rich > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Amelia Stein > Sent: Sunday, April 15, 2007 1:44 PM > To: Programming forum > Subject: Re: [Jprogramming] J script files > > So how do you actually "scan" in a number from standard > input? What is the > syntax? Whether or not it is of good form in J, I have a > presentation to do > tomorrow where I need input from the keyboard. > > On 4/15/07, Devon McCormick <[EMAIL PROTECTED]> wrote: > > > > Randy - > > > > I think it's a mis-characterization to say that J "isn't > meant for user > > input". > > In fact, due to its interpretive nature, J handles user > input beautifully > > compared > > to any conventional language, if you use the language > itself. Of course, > > as > > an avid APLer, I'm sure this isn't news to you. > > > > But this prompt-based notion won't die, no matter how crippled it is > > compared > > to simply using native J. Take, for instance, the outline > of the program > > that > > Amelia is writing: allow someone to enter some numbers, > then return some > > descriptive statistics about them. Using J, I would naturally do > > something > > like > > > > (<./,>./,mean,stddev) 97.1 4.7 33 1.3 22 60 27.6 96.4 87.1 67.5 > > 1.3 97.1 49.67 36.744585 > > > > However, as Amelia's professor has constrained the problem, > the "correct" > > session might look more like this: > > > > Enter some numbers: 97.1 4.7 33 1.3 22 60 27.6 96.4 87.1 67.5 > > ** Error: can only accept 5 numbers. > > Enter some numbers: 97.1 4.7 33 1.3 22 > > The minimum is 1.3. > > The maximum is 97.1. > > The mean is 31.62. > > The standard deviation is 38.813876. > > > > or some such limited, simplistic implementation. Notice > how thoroughly > > inadequate this prompt-based paradigm is for getting any > serious work > > done: > > it's probably constrained to some fixed number of entries > or necessitates > > added complexity to acommodate a variable number of > entries. Furthermore, > > an input mistake can only be corrected by re-typing the > entire set of > > entries > > and the result can only be used by manually transferring it. > > > > (Of course, using a spreadsheet may also be a good way to > handle a problem > > like this.) > > > > This prompt+manual input notion is a lousy paradigm that is > encumbered by > > widely-accepted, unnecessary limitations of the past 50 > years. Today, we > > have > > scalpels and laser beams but most people still insist on > using sticks and > > rocks. > > > > However true all this all is, the problem of user input > seems to be a > > recurring one in J. > > Those of us who use the language a lot have solved it for > ourselves but it > > recurs > > regularly for beginners. We've talked about this a bit in > the NYCJUG and > > the > > consensus seems to be 1) use file-based input, or 2) use a > spreadsheet > > front-end. > > > > One other idea is to use the GUI-building capabilities of some other > > language, > > like Java or VB, and > > interface the resulting GUI with J. Until get something like > > this fully fleshed out on the Wiki, we may have to make do > by referring > > people to > > the character-based solutions for Amelie that came out of > this thread. > > > > Devon > > > > On 4/15/07, ramacd <[EMAIL PROTECTED]> wrote: > > > > > > > > > > > > Dan Bron wrote: > > > > This is easy to see if we take a reductionist approach: > a single J > > > > token is either a built-in J primitive, or it's a > user-defined name > > > > with an arbitrary definition. Primitives never change > their definition > > > > (good thing!). And the dictionary of J explicitly states, at > > > > http://www.jsoftware.com/help/dictionary/dict2.htm that: > > > Primitives don't change their definition over a single > version of J, > > > that is true. Over multiple versions it is a different > story. In fact, > > > I long ago coined a term ("getting henked") for the suffering one > > > undergoes when one assumes upward compatibility. > > > > > > On the original idea of this thread, having a REPL facility, which > > > doesn't come in primitive-only J, doesn't strike me as a > stretch of its > > > capabilities. I do wonder at the (if you want a > responsive computer, > > > don't let a user near J) attitude, and where it comes > from. Amelia's > > > note that J "isn't meant for user input." crystallizes a > big misgiving I > > > have about J, even though I have been pro-J since J has > been around. > > > > > > >: ... > > > > > > > ---------------------------------------------------------------------- > > > For information about J forums see > http://www.jsoftware.com/forums.htm > > > > > > > > > > > -- > > Devon McCormick, CFA > > ^me^ at acm. > > org is my > > preferred e-mail > > > ---------------------------------------------------------------------- > > For information about J forums see > http://www.jsoftware.com/forums.htm > > > ---------------------------------------------------------------------- > For information about J forums see > http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
