vim-hew

Vim/Neovim syntax highlighting and editor support for the Hew programming language.

Use the Hew v0.6.1 SDK for the current released compiler and formatter. This plugin highlights generic closures such as |<T: Eq> left: T, right: T| -> bool { left == right } and callable types such as fn<T: Eq>(T, T) -> bool; highlighting does not replace compiler diagnostics.

Installation

lazy.nvim (Neovim)

{ 'hew-lang/vim-hew' }

vim-plug

Plug 'hew-lang/vim-hew'

packer.nvim (Neovim)

use 'hew-lang/vim-hew'

Manual

Copy the contents to your Vim runtime directory:

# Vim
mkdir -p ~/.vim && cp -r syntax ftdetect ftplugin indent ~/.vim/

# Neovim
mkdir -p ~/.config/nvim && cp -r syntax ftdetect ftplugin indent ~/.config/nvim/

Features

• Full syntax highlighting (keywords, types, actors, supervisors, strings, numbers, comments, operators, attributes)
• Filetype detection for .hew files
• Comment formatting (//, /* */)
• Indentation support (cindent-based)

Formatting

If you have the hew compiler installed, you can format the current buffer with:

:%!hew fmt --stdin

The --stdin form formats the current buffer, including unsaved edits. Do not pass % to the filter: a path argument formats the disk file in place and prints a status message that replaces the buffer. If the filter reports an error, undo it with u before saving.

For format on save, preserve the buffer when formatting fails and stop the write rather than saving formatter error output:

function! HewFormat() abort
  let formatted = systemlist('hew fmt --stdin', join(getline(1, '$'), "\n") . "\n")
  if v:shell_error != 0
    throw 'hew fmt failed: ' . join(formatted, "\n")
  endif
  let view = winsaveview()
  call setline(1, formatted)
  if line('$') > len(formatted)
    execute (len(formatted) + 1) . ',$delete _'
  endif
  call winrestview(view)
endfunction

autocmd BufWritePre *.hew call HewFormat()

hew must be on the editor's PATH. Formatting is separate from language-server features; this plugin supplies syntax highlighting, filetype detection and indentation, and does not start an LSP client.

Syntax verification

Run the syntax smoke test with Vim:

vim -Nu NONE -i NONE -n -es -S test/syntax.vim
HEW_COMPILER=/path/to/hew python3 test/formatting.py

The fixture covers dotted paths, .{ } imports, and contextual .Variant forms, consuming receivers, generators and plain stream iteration. Retired syntax is highlighted as an error; the compiler names the legacy path and turbofish diagnostics E_PATH_LEGACY_SEPARATOR and E_LEGACY_TURBOFISH; removed glob imports use E_IMPORT_GLOB_REMOVED.

License

Apache-2.0