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Learn C and build your own Lisp

buildyourownlisp.com

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Re: Learn C and build your own Lisp

#81

Post by rasur »

gmfawcett wrote: post #26

If you're interested in this, you might also enjoy "Write yourself a Scheme in 48 hours." It uses Haskell rather than C as the implementation language. https://en.wikibooks.org/wiki/Write_Yourself_a_Scheme_in_48_...

I am working through this slowly - it is excellent (although I find myself referring to the Haskell report tutorial too, when I find something that needs further clarification).

A word of warning - the pdf version is not as accurate as the html version. Prepare for some head scratching if you use the pdf.

Re: Learn C and build your own Lisp

#84

Post by Iftheshoefits »

orangeduck wrote: post #31
pjmlp wrote: post #17

Please don't. Rather pick something like "Compiler Construction" from Niklaus Wirth and learn how to write compilers using memory safe system programming languages. http://www.ethoberon.ethz.ch/WirthPubl/CBEAll.pdf

I wrote this book over several months. It took a few days to get the courage to share it online. It probably took you about 20 seconds to not read my book, dismiss it, and post a comment telling other to do the same. If you think an alternative is better that's fine, but how about you take an extra 20 seconds to think about the situation next time you are going post a comment.

The person you're responding to has a history of hating on C around here. I wouldn't take what he wrote personally (easier said than done, I know). That said, I offer the following:

Almost any language can be (ab)used in an "unsafe" manner. Conversely, it is entirely possible to create elegant, efficient, and safe code using C, and there is no particular reason to not use C for this project. In fact, C is marvelous in its simplicity and is an excellent candidate for it.

On a scale of 1 to 10 I'd put my skill with C++ around a 6 or 7. For C I'd go lower, around 3 or 4. I appreciate the work you put into this, and I intend to read your book to help me improve my skills with C.

So thanks for your effort.

Re: Learn C and build your own Lisp

#85

Post by kyllo »

agentultra wrote: post #57
donniezazen wrote: post #52

I am new to programming. What is it so special about Lisp that I keep hearing about it in Hacker's News (often in Machine Learning and from old programmers)?

You will get different answers from different people. There doesn't appear to be any commonly accepted universal truths in Lisp (otherwise we'd all be programming in some variant of it by now). However there are plenty of good ideas which many more popular languages have adopted. What made it special for me was discovering the link between symbolic computing and the lambda calculus. The kernel at the center of every…

Yeah, and it's important to remember that programming languages are for humans, after all. So if this paradigm is easier to reason about and makes you more productive (than coding in something imperative like C or Java or Python), then that makes it a great language for you.

Re: Learn C and build your own Lisp

#86

Post by chriswarbo »

Nav_Panel wrote: post #40
jnbiche wrote: post #15

Earlier quoted context omitted.

Oh wow! This is extremely useful, thank you. I've been wanting to develop my own statically-typed language, but almost all tutorials on the web are for dynamic languages with little mention given to type systems. I've already started a toy dynamically-typed language, but the step up from that to a static language seems significant, particularly given the dearth of information I can find on the web (aside from dense a…

Here's a different book you might be interested in ("Practical Foundations for Programming Languages": http://www.cs.cmu.edu/~rwh/plbook/book.pdf It gets pretty math-heavy at times, at least in the beginning (you can probably skip the first chapter if it's too rough), but ultimately the book is about programming language design and different ways of designing and evaluating typed (or un(i)typed) languages. It also lo…

PFfPL is a great book. It manages to present many seemingly different language features in a surprisingly unified way.

It's very opinionated at times (usually against anything "dynamic", eg. typing and binding ;) ) but I think it's worth it for the clarity that it allows. Of course, Bob Harper has the clout to back up those opinions!

Re: Learn C and build your own Lisp

#88

Post by aidenn0 »

cliveowen wrote: post #13
unwind wrote: post #7

I always find it so hard to help out proof-reading code for causes like this. Often, the code is more complicated than I find reasonable, while omitting things that make a lot of sense in "real" code, and it's very hard to know as an outside reader what the exact motivation for each decision was, by the author. A few such things that caused me to WTF: The initial few examples use a pointlessly static and global line…

If there's one thing that I really can't stand are magic numbers. The K&R says to always use constants, which means this has been a good practice for more than 40 years and I really can't grasp how someone can hope to teach something when his own knowledge lacks the basics.

Also lots of people still use #define for magic numbers; I learned C in the late 80s with a book by Thomas Plum, and it recommended using enum whenever possible in preference of #define.

The reason given was superior debug support. Debuggers have gotten better at handling #defines, but #defines are still second class citizens. I've personally worked with a debugger that could precisely find all references of an enum, but only grep for a #define. In code with lots of conditional compilation, that makes a huge difference.

Re: Learn C and build your own Lisp

#90

Post by wedesoft »

I was trying to implement an interpreter for a minimal (lazy) language in C [1]. It uses Church encoding and other encodings. E.g. here are the definitions of false, true, identity, and pair:

    f_ = proc_self(lambda(v0));
    t_ = proc(lambda(v1), f());
    id_ = proc(v0, f());
    pair_ = lambda3(op_if(v0, v1, v2));
For the moment I gave up on it though but maybe it might serve as inspiration ;)

[1] https://github.com/wedesoft/blc/blob/master/src/x.c#651

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