mjambon

A guide to using Graphite's stacked PRs for GitHub users

If you're not sure how to take advantage of Graphite but your colleagues are raving about it, here's what I wish I was told from the beginning when we started experimenting with Graphite at Semgrep. I propose a workflow that makes it easy to revise previous commits, reduces conflicts, and avoids having unrelated changes in the same PR.

A stack of what?

A stack of pull requests isn't really a stack of pull requests, it should be treated as a stack of changes. Even though technically each change in the stack ends up being a GitHub pull request as we know it, a stack of changes functionally is the equivalent of one large traditional GitHub pull request implementing a new feature in multiple steps.

mjambon

module Generic = struct
  (* generic expr type used for matching *)
  type expr =
    | A
    | B of expr * expr [@lang a]
    | C of expr [@lang b c]
    | Unsupported of string [@fallback]
end

(*** Generated from the above ***)

mjambon

type kind = [
  | Root (* class name conflict *)
  | Thing of int
  | WOW <json name="wow">
  | Amaze <json name="!!!"> of string list
]

type root = {
  id: string;
  await: bool;

mjambon

from typing import List
import json

# type t = A | B of int

class T:
    pass

class T_A(T):
    def __repr__(self):

mjambon

(* Arithmetic with Binary numbers (unsigned, arbitrary precision!) *)

type digit = Zero | One
type t = digit list

let rec eq a b =
  match a, b with
  | [], [] -> true
  | da :: a, db :: b when da = db -> eq a b
  | _ -> false

mjambon

(*
   Evaluate the performance of a stack-safe implementation of List.map.

   Run with:

     ocamlopt -o list_map unix.cmxa list_map.ml
     ./list_map
*)

open Printf

mjambon

(*
   Extra string operations for OCaml
   
   Conventions:
   - all operations are failsafe: no exceptions are raised
   - negative index i is equivalent to positive index (length - i)
   - from/until indicate inclusive ranges like in 'for' loops
     (for i = from to until do ... done)
   - does not replicate or override the standard String module

mjambon

#! /usr/bin/env bash
#
# Remove a single git commit from history.
#
set -eu

usage() {
    cat <<EOF
Usage: $0 <commit ID>

mjambon

(* Generated by ocaml-tree-sitter. *)
(*
   typescript grammar

   entrypoint: program
*)

open! Sexplib.Conv
open Tree_sitter_run

mjambon

(**
   Boilerplate to be used as a template when mapping the java CST
   to another type of tree.
*)

(* Disable warnings against unused variables *)
[@@@warning "-26-27"]

(* Disable warning against unused 'rec' *)
[@@@warning "-39"]