Show HN: A Demo IDE for Scheme (opens in new tab)

(kennethfriedman.org)

97 pointskennethfriedman6y ago17 comments

17 comments

OP here.

This IDE started as a final project in Gerry Sussman's LISP class at MIT.

When programming and debugging, you often want to know what your code is going to do without the possibility of unintended side effects (state change) by actually running the code.

Towards this goal, we added a concept we call "preview execution." That is: you can preview the output of code in our IDE simply by highlighting a section of code. The IDE will show the output of the highlighted section, but when you de-select the section, there are no side effects: no state is changed in the Scheme instance.

It's downloadable as a Mac app, but also open source. Would love to hear people's thoughts on it!

quelltext6y ago

What about side-effects that cannot easily be contained, e.g. HTTP requests sent from your code, DB writes?

I don't think the goal can be achieved pragmatically for many types of modern applications generally. Maybe offering some sort of debug snapshotting and mocking layer for things like that and libraries to implement might be an idea. The debugger should then also be able to identify for which parts preview execution can be done and for which ones it's not possible to contain side-effects.

e12e6y ago

> but when you de-select the section, there are no side effects: no state is changed in the Scheme instance.

So if your code deletes itself on disk - that code path will run in a sandbox, and roll back? Or are you talking only of state contained/managed by scheme (eg not the os) like global data structures etc?

e12e6y ago

Ah, from tfa:

> How Preview Execution Works

> Under the hood, preview execution works by using Scheme environments.

> When code is highlighted, Toski duplicates the current environment and executes the code. Then, when the cursor is moved or the code is de-selected, Toski removes the new environment, returning the instance to the previous state.

Which makes sense - but it would be cool if it automagically mocked all external calls... ;)

1 more reply

sansnomme6y ago

Chrome's JavaScript console does this too. Type in e.g. an array transform code and the output should appear below in faded text without you having to click enter.

agumonkey6y ago

Ever thought about merging it with property based testing (ala quickcheck) ?

0xferruccio6y ago

You might find the work Chris Granger did on Light Table quite interesting ( https://www.youtube.com/watch?v=H58-n7uldoU )

I really liked the first version and did some research some time ago on how to make this usable by a wider audience: https://ferrucc.io/posts/a-new-ide/

dap2326y ago

This one shows function calls and linked lists in case you find it interesting: http://davidpilo.com/pvts/

jedberg6y ago

It says "Can't find scheme, contact the developer". I figure I'd contact you here so that others can see the answer too.

I have MIT scheme installed on the system. How do I tell it where to find Scheme?

Or better yet, any chance you can just package up the interpreter with the IDE, or make that an optional download?

gkbrk6y ago

Not sure if there's anything wrong with the page or not, but when I visited it locked up my machine and used a lot of RAM until Firefox killed the tab.

slim6y ago

my guess is it uses css skew (a rarely used css function). update your firefox

FraserGreenlee6y ago

The previewing execution is cool, reminds me of my Python debugger https://marketplace.visualstudio.com/items?itemName=fraser.l...

dimitar6y ago

Preview execution is pretty cool. Looks similar to the instarepl from nightcode: https://sekao.net/nightcode/

Y_Y6y ago

Isn't such a thing already possible in emacs?

jhorsager6y ago

In Emacs you have to actively evaluate expressions (i.e., C-x C-e). This IDE apparently will evaluate highlighted expressions without interaction on the user's part. That said, you could easily write an elisp routine to do the same (evaluate region when point and mark set).

thom6y ago

Yeah this is fairly trivial to replicate. Plus if you’re using Clojure there aren’t many side effects anyway so the effect of rolling back is largely the same.

j / k navigate · click thread line to collapse

17 comments

kennethfriedmanOP6y ago

OP here.

This IDE started as a final project in Gerry Sussman's LISP class at MIT.

When programming and debugging, you often want to know what your code is going to do without the possibility of unintended side effects (state change) by actually running the code.

It's downloadable as a Mac app, but also open source. Would love to hear people's thoughts on it!

quelltext6y ago

What about side-effects that cannot easily be contained, e.g. HTTP requests sent from your code, DB writes?

e12e6y ago

> but when you de-select the section, there are no side effects: no state is changed in the Scheme instance.

e12e6y ago

Ah, from tfa:

> How Preview Execution Works

> Under the hood, preview execution works by using Scheme environments.

Which makes sense - but it would be cool if it automagically mocked all external calls... ;)

1 more reply

sansnomme6y ago

Chrome's JavaScript console does this too. Type in e.g. an array transform code and the output should appear below in faded text without you having to click enter.

agumonkey6y ago

Ever thought about merging it with property based testing (ala quickcheck) ?

0xferruccio6y ago

You might find the work Chris Granger did on Light Table quite interesting ( https://www.youtube.com/watch?v=H58-n7uldoU )

I really liked the first version and did some research some time ago on how to make this usable by a wider audience: https://ferrucc.io/posts/a-new-ide/

dap2326y ago

This one shows function calls and linked lists in case you find it interesting: http://davidpilo.com/pvts/

jedberg6y ago

It says "Can't find scheme, contact the developer". I figure I'd contact you here so that others can see the answer too.

I have MIT scheme installed on the system. How do I tell it where to find Scheme?

Or better yet, any chance you can just package up the interpreter with the IDE, or make that an optional download?

gkbrk6y ago

Not sure if there's anything wrong with the page or not, but when I visited it locked up my machine and used a lot of RAM until Firefox killed the tab.

slim6y ago

my guess is it uses css skew (a rarely used css function). update your firefox

FraserGreenlee6y ago

The previewing execution is cool, reminds me of my Python debugger https://marketplace.visualstudio.com/items?itemName=fraser.l...

dimitar6y ago

Preview execution is pretty cool. Looks similar to the instarepl from nightcode: https://sekao.net/nightcode/

Y_Y6y ago

Isn't such a thing already possible in emacs?

jhorsager6y ago

thom6y ago

Yeah this is fairly trivial to replicate. Plus if you’re using Clojure there aren’t many side effects anyway so the effect of rolling back is largely the same.

j / k navigate · click thread line to collapse