Pact Language Server

Pact is an open-source, Turing-incomplete smart contract language that has been purpose-built with blockchains first in mind. Pact focuses on facilitating transactional logic with the optimal mix of functionality in authorization, data management, and workflow.

The LSP server requires Pact 4.6

Supported Features

The Pact language server currently supports the following features:

• Document diagnostics Every time a file is opened or saved, the file is analyzed using the pact executable and diagnostic information is supplied.

• Completion of natives While typing, the LSP server provides completions for natives.

• Documentation of natives Hovering over natives populates the documentation.

Server Configuration

The LSP server needs to access the pact executable. Therefore, users can configure the path of the executable at server initialization by sending a configuration as follows:

{
  "pact": {
    "pactExe": "/path/to/pact"
  }
}

Building from Source

Dependencies

• (Mac only) Homebrew: brew install git
• (Linux/Mac) Installer
• Pact executable (see Instructions)

To get the code, you can go here. Once you have the code, we can pick a build tool.

Building with Cabal

Cabal is the preferred way to manage packages by the Haskell community. You will need a version of GHC installed on your machine to use it.

Dependencies

• ghc >= 9.6 (Haskell compiler) and cabal >= 2.2 (Haskell build-tool)
  • The easiest way to get this is to install it using (Linux/Mac) ghcup and issue ghcup install 9.6.2, followed by ghcup install-cabal.
  • ghc may also be installed via brew, issuing brew install ghc and brew install cabal-install.

To build a Pact LSP binary:

# Only necessary if you haven't done this recently.
cabal v2-update

# Build the project.
cabal v2-build

This will install a runnable version of the Pact LSP, which you can run via:

cabal v2-exec pact-lsp

Alternatively, running cabal v2-install exe:pact-lsp inside this repository's root will install the binary to ~/.cabal/bin/, which you may need to add to your path. Then, you can call pact-lsp as-is.

Building with Nix

The fastest way to build and run Pact is to use the Nix package manager which has binary caching capabilities that allow you to download pre-built binaries for everything needed by Pact. We use nix flakes (which requires users to set --experimental-features "nix-command flakes") to build pact and its dependencies. For detailed instructions see our wiki.

To build the Pact executable:

nix build

When the build is finished, you can run the Pact LSP with the following command:

./result/bin/pact-lsp

Troubleshooting

The pact-lsp executable accepts the --debug flag to generate a log file which can be used to further debug issues.

Editor Configuration

Emacs

Using eglot:

(require 'pact-mode)
(require 'eglot)

(with-eval-after-load 'eglot
  (add-to-list 'eglot-server-programs '(pact-mode . ("pact-lsp" ))))

(add-hook 'pact-mode-hook 'eglot-ensure)

Using lsp-mode

(require 'pact-mode)
(require 'lsp-mode)

(add-to-list 'lsp-language-id-configuration '(pact-mode . "pact"))
  (lsp-register-client (make-lsp-client
                           :new-connection (lsp-stdio-connection "pact-lsp")
                           :activation-fn (lsp-activate-on "pact")
                           :server-id 'pact-lsp
                           :major-modes 'pact-mode)
                       )
 (add-hook 'pact-mode-hook 'lsp-deferred)
  )

or, in Doom Emacs

(after! (:all pact-mode lsp-mode)
  (add-to-list 'lsp-language-id-configuration '(pact-mode . "pact"))
  (lsp-register-client (make-lsp-client
                           :new-connection (lsp-stdio-connection "pact-lsp")
                           :activation-fn (lsp-activate-on "pact")
                           :server-id 'pact-lsp
                           :major-modes 'pact-mode)
                       )
  )

(after! pact-mode
  (add-hook 'pact-mode-hook (lambda () (lsp-deferred)))
  )

Vim

Using vim-lsp:

if (executable('pact-lsp'))
  au User lsp_setup call lsp#register_server({
      \ 'name': 'pact-lsp',
      \ 'cmd': {server_info->['pact-lsp']},
      \ 'whitelist': ['pact'],
      \ })
endif