cobbler

cobbler refactors programs to use library functions.

It currently supports refactoring:

• Elm programs to use functions like those found in the Elm Standard Library (e.g. map and filter); specifically, the ones defined in this file
• Python programs to use the NumPy high-performance computing library

How to run: First, install cobbler's dependencies by following the instructions in DEPENDENCIES.md; then, you can run cobbler via the cobbler script in the root of this repository.

For help: Run ./cobbler --help.

For information about how cobbler works: Please see our PLDI 2024 paper!

Examples

Elm

withDefault/map

Input:

main : (Int -> Int) -> Maybe Int -> Int
main f mx =
 case mx of
   Nothing -> 0
   Just x -> f (f x)

Output:

main : (Int -> Int) -> Maybe Int -> Int
main f mx =
    mx
        |> Maybe.map (\x -> f (f x))
        |> Maybe.withDefault 0

concat/map/filter

Input:

main : (String -> Bool) -> (String -> List Int) -> List String -> List Int
main p f list =
  case list of
    [] -> []
    head :: tail -> if p head then f head ++ main p f tail else main p f tail

Output:

main : (String -> Bool) -> (String -> List Int) -> List String -> List Int
main p f list =
    list
        |> List.filter p
        |> List.map f
        |> List.concat

Python

Dot product

Input:

s = 0
for i in range(len(x)):
    s += x[i] * y[i]
s

Output:

s = np.sum(np.multiply(x, y[:len(x)]))
s

Rolling sum

Input:

y = np.zeros(len(x) - WINDOW_SIZE + 1)
for i in range(len(y)):
    s = 0
    for j in range(WINDOW_SIZE):
        s += x[i + j]
    y[i] = s
y

Output:

y = np.convolve(x, np.full(WINDOW_SIZE, 1), mode="valid")
y

Additional information

• For information about how this project is structured, please see ARCHITECTURE.md.
• For information about the artifact evaluation process for our PLDI 2024 paper, please see ARTIFACT_EVALUATION.md.

Art acknowledgments

• Thanks to Anna Christenson for the logo!
• Thanks to Patrick Gillespie for the Text to ASCII Art Generator and myflix for the "Sweet" ASCII art font.