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A Friendly Introduction to Racket

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Re: A Friendly Introduction to Racket

#41

Post by AnimalMuppet »

dented42 wrote: post #30
allthetime wrote: post #18

Earlier quoted context omitted.

It is rich with information, to the point, and presented in a way that a motivated and competent reader can immediately know something about and be useful with racket. That’s how it was for me anyways; someone who didn’t know anything about racket before reading through this. Wtf kind of intro to a programming language doesn’t include syntax rules? We are all informed, experienced, technologically inclined people her…

> Wtf kind of intro to a programming language doesn’t include syntax rules? Given that most languages don’t have syntax rules or anything like it, I’m gonna go out on a limb and say that most language introductions/overviews/tutorials don’t mention it.

Most? I question that.

In fact, what languages can you say do not have syntax rules?

Re: A Friendly Introduction to Racket

#42

Post by ux266478 »

Nothing against Lisp, but to correct the record:

> For decades, Lisp was the language of artificial intelligence. [...] Then came the "AI winter," funding dried up, and Lisp went from star to cult language.

Lisp had fallen from relevance before then. Only the United States was still using it, and mostly out of technical debt and a stubborn refusal to move on. Prolog displaced it in the late 1970s, and even within the US, the Lisp part was an unfortunate implementation detail to get to a Prolog-shaped object. It's not surprising that the US fell way behind Japan in this area in the 1980s. Anybody who would imply they would take a Lisp machine over a PIM is either not interested in symbolic computation and just likes Lisp, or they're doing so out of total ignorance of how much more advanced the PIMs were for symbolic AI.

The cutting edge was with Prolog, and that's still the case today. Nobody's researching MIL in Lisp, even in America.

Re: A Friendly Introduction to Racket

#44

Post by jibal »

jqpabc123 wrote: post #36
GregBuchholz wrote: post #31

> no special syntax for anything. (list '(1. . #\#) -5/6+7.s-8i `(1 ,@2) 1@1 ;hmmm, no unquote splicing comma ;-) 10# ;surprised? (list #i+1 +1i 1+i) ;complicated or complex? #e-1e10i ;Old MacDonald? "(* 9 10)" #())

It looks more like a "program" for an HP15c pocket scientific calculator. Not necessarily a bad thing but also not exactly what I would call "expressive". You may be able to build anything you want --- which may be efficient when communicating with the machine. But I wonder about now well this would communicate with other programmers.

It's not a program, it is (obviously) a totally unrealistic hodgepodge expression for a list of constant values that simply demonstrates the literal syntax for a variety of types of values (real numbers, dotted pairs, rational numbers, complex numbers, polar coordinates, etc. -- Racket is unusually expressive in the types of literals). Your comment demonstrates something typical of HN, and it's not a good thing. It's as if in a discussion about C someone posted, without explanation, an entry from the Obfuscated C contest and then someone else, making zero effort to understand what was posted, said that it looked like line noise and questioned whether C is conducive to communication between programmers.

Re: A Friendly Introduction to Racket

#45

Post by layer8 »

eru wrote: post #39
layer8 wrote: post #19

Earlier quoted context omitted.

I don’t find it appealing when everything looks the same irrespective of purpose and context.

Seems like a non-sequitur.

How so? Homoiconicity means that everything uses the same form of representation, and I’m familiar with how these things look in Lisp.

Re: A Friendly Introduction to Racket

#46

Post by nilslindemann »

GregBuchholz wrote: post #31

> no special syntax for anything. (list '(1. . #\#) -5/6+7.s-8i `(1 ,@2) 1@1 ;hmmm, no unquote splicing comma ;-) 10# ;surprised? (list #i+1 +1i 1+i) ;complicated or complex? #e-1e10i ;Old MacDonald? "(* 9 10)" #())

Curious, how would look that in Python?

Re: A Friendly Introduction to Racket

#47

Post by aobdev »

AnimalMuppet wrote: post #41
dented42 wrote: post #30

Earlier quoted context omitted.

> Wtf kind of intro to a programming language doesn’t include syntax rules? Given that most languages don’t have syntax rules or anything like it, I’m gonna go out on a limb and say that most language introductions/overviews/tutorials don’t mention it.

Most? I question that. In fact, what languages can you say do not have syntax rules?

Python and Java do not have any similar constructs

Re: A Friendly Introduction to Racket

#48

Post by soegaard »

GregBuchholz wrote: post #31

> no special syntax for anything. (list '(1. . #\#) -5/6+7.s-8i `(1 ,@2) 1@1 ;hmmm, no unquote splicing comma ;-) 10# ;surprised? (list #i+1 +1i 1+i) ;complicated or complex? #e-1e10i ;Old MacDonald? "(* 9 10)" #())

Yeah - the number syntax is pretty cool.

    #i is the prefix for inexact
    #e is the prefix for exact
So `#e0.1` is exact 0.1 which means it will be read as an exact fraction 1/10 and `#i0.1` will be read as a floating point number.

The `i` in `8i` is the imaginary unit. The `1@1` is the polar notation for complex numbers.

The `10#` is a compatibility remain (the Scheme authors wanted a way to see how many signifant digits were known. In `10#` there 2. So `#` stands for "some digit". In most implementations this is read as 0. More details at [1]

An `#` followed by a list datum is read as a vector. Thus `#()` is an empty vector and `()` is an empty list.

[1] https://stackoverflow.com/a/10936403/23567

Complicated? Well, to support both inexact (floating point) and exact numbers (bignums and fractions) it makes sense to have `#i` and `#e` to explicitl choose. The default is (more or less): numbers with . are inexact the others are exact.

Re: A Friendly Introduction to Racket

#49

Post by Syntonicles »

GregBuchholz wrote: post #31

> no special syntax for anything. (list '(1. . #\#) -5/6+7.s-8i `(1 ,@2) 1@1 ;hmmm, no unquote splicing comma ;-) 10# ;surprised? (list #i+1 +1i 1+i) ;complicated or complex? #e-1e10i ;Old MacDonald? "(* 9 10)" #())

At first I was frustrated by this comment, having a fair amount of Lisp experience failing to grok the examples. In less than one minute I was able to locate, download and install the latest Racket and was in a REPL. There really are no excuses.

This was a wild ride. I'm torn on whether this feels like the Reader is bloated/polluted or whether this is the coolest numerical parser I've ever used. You can really do a lot to coerce the these numbers just by inserting an {o,s,e,i,b,#} into the number, with different semantics depending on the position of the character.

Somewhat overwhelming, I can only hope there's some elegance underlying it all...

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