Motivation

• We want a richer dependency resolution system in Leo. Leo users should be able to import programs from chain/local file system as opposed to requiring .leo source files.

Components:

1. Specify import configurations in program.json
2. leo build leverages retriever module to pull programs from network/FS
3. Generate leo.lock file to house the dependency configuration
4. disassembler.rs to convert Aleo instructions into valid stub
5. Type checking modification to maintain soundness
6. Codegen modification to print nested imports properly

Retriever Design

Modifications to ~/.aleo file structure

• .aleo/registry:

  • .aleo/registry/git : Where .aleo files from github.com are stored
  • .aleo/registry/testnet3: Where .aleo files from the network are stored
  • Note that new folders can be added for different networks like ./mainnet

• Suppose building leo project dex and call leo build with dex/program.json set to:

{
  "program": "dex.aleo",
  "version": "0.0.0",
  "description": "",
  "license": "MIT",
  "dependencies": [
    {
	  "name": "credits.aleo",
	  "location": "network",
		"network": "testnet3"
    },
		{
		"name": "foo.aleo",
	  "location": "git",
		"url": "https://github.com/alice/foo.git"
		"branch": "bar"
		"rev": "3ab873bd89de"
		},
    {
	  "name": "board.aleo",
	  "location": "local",
	  "path": "/User/bob/home/work/board", 
    },
  ]
}

Specification and example flow

1. Retrieve imports based on configurations specified in dex/program.json:
   • Must keep track of nested programs trying to build, and throw error for circular dependencies
   • Location variations:
   • "location": "network":
     • Check if credits.aleo cached already in ~/.aleo/registry/testnet3/credits.aleo
   • Retrieve from network:
     • Store copy in `~/.aleo/registry/testnet3/credits.aleo``
     • Update leo.lock
     • "location": "local": TODO
       • Build the directory specified (ex "path": "~/work/board") if no aleo program in ~/work/board/build/main.aleo
       • Other wise use ~/work/board/build/main.aleo
       • Cache in .aleo and update leo.lock
     • "location": "git": TODO
       • Example: "url": "<https://github.com/alice/foo.git>"
       • Check if board.aleo cached already as ~/.aleo/registry/git/pranav/foo/board.aleo
       • Otherwise retrieve from network and cache
       • Allow them to specify based on commit + branch
2. Move a copy of the retrieved import(s) into dex/build/imports/
3. Convert all imported programs to AST before start parsing main.leo

Suggested user behavior

• Ideal: (in future)
  • User writes leo add credits.aleo kicks off network retrieval + caching process
  • Default to network for simplicity, but ability to use git or local too
• For now:
  • User manually edits program.json
• Its ok if user manually edits {project}/build/imports/ as that is regenerated every time build is invoked.
• Assume that user will not modify ~/.aleo/ & leo.lock

Future features

• Add support for local and git dependencies
• Relax shadowing:
  • Should be able to import two functions of same name from different programs
• Leo add {program} CLI