gerbil/community

All things Gerbil Scheme

Jason Felice

@eraserhd

if you think of it as "a different begin-amb", it makes sense.

vyzo

@vyzo

yes, but we do have begin-amb and we can do more interesting things with it :)

I really like having it inside the code and saying (all-of x) instead of having to say (all-of (let (blah (amb ...) ...) ...)

Jason Felice

@eraserhd

Yeah, that is definitely nice.

vyzo

@vyzo

alright, the extra parameter trick works

I run it 100 times and no failure

vyzo

@vyzo

alright, here is #531

now it should work reliably

check out this example:

(begin-amb-random (let ((x (amb 1 2 3)) (y (amb 1 2 3))) (required (> x y)) (all-of (cons x y))))

it's very declarative

Jason Felice

@eraserhd

ok, building now

vyzo

@vyzo

also note that thanks to begin-amb and the use of parameters we can have nested ambs very easily

which is not possible in chicken, because they use global variable mutation to track continuations

Jason Felice

@eraserhd

that is very nice

vyzo

@vyzo

plus multiple threads doing ambs at the same time

don't try that in chicken :)

vyzo

@vyzo

Actually I think I should use amb-end in one-of as well

it's really nice that we have the second parameter

Jason Felice

@eraserhd

still building... so how does emacs detect that a file is gerbil instead of scheme?

Do you configure emacs so that all .ss files are gerbil?

amb-collect is working for me (except, of course, that I'll need to handle the no-values case)

vyzo

@vyzo

I am also exporting the exception predicate now

will push shortly

updating the documentation

so that you can catch the exception

and do something meaningful in the no values case

alright, pushed

is it just me or is github acting up for everyone today?

so for the emacs detection

vyzo

@vyzo

1) I have set .ss files to default to gerbil mode

2) I also use the modline, all gerbil code has -*- Gerbil -*- in it

so handling the no values case:

(try do-some-amb-stuff-and-collect (catch (amb-exhausted? e) []))

vyzo

@vyzo

also note that all-of still works outside the amb expression

this works:

(begin-amb-random (all-of (let ((x (amb 1 2 3)) (y (amb 1 2 3))) (required (> x y)) (cons x y))))

so we are backwards compatible

and if the constraint is not satisfied, it will return the empty list

vyzo

@vyzo

alright, merged

vyzo

@vyzo

and I am off to bed

night fellas!

François-René Rideau

@fare

I would like two infix operators so I can wrap a form on the left or right within another form.

e.g. x #> y ⇒ (y x) and f #< x ⇒ (f x) or some such

looking at the srfi 1 thing... there might be an issue with wrong dependencies in the spec

François-René Rideau

@fare

oops, I forgot some srfi/ prefixes in extra dependency paths

François-René Rideau

@fare

^ fixed in #532

vyzo

@vyzo

ah, that explains it

vyzo

@vyzo

so for the infix operators, they have to be supported by the reader first and foremost

Jeffrey M. Young

@doyougnu

@fare I got it working, I was tyring to get a local build of gerbil to run in nix-shell, like nix-shell shell.nix --run "cd src && ./build.sh" not a build from nixpkgs or your branch. I got it working thanks to @thibran.