Language tools

Language servers, diagnostics, formatters, and adding a language in a few lines of YAML.

Language servers#

Hm speaks the Language Server Protocol: diagnostics, hover, completion, go to definition and implementation, find references, rename, document symbols and formatting. The Problems panel lists every diagnostic, and the footer shows the server a file uses.

When a server or formatter is missing, Hm offers to install it with one click (go install, brew, npm, ...).

Formatters#

Formatters are set per language and run on save, on demand or after paste. A formatter either reads the buffer on standard input and writes the result, or rewrites the file in place ({file} is its path):

languages:
  go:
    formatters:
      - { command: gofmt, args: ["-w", "{file}"], on: [save, manual] }

Adding a language#

Adding a language, server or formatter is a few lines of YAML under languages:. View defaults in Settings shows how the built-in languages are set up, which is the best template for a new one.

Inline completions#

AI completions show ghost text at the caret; Tab accepts and Esc dismisses. They use a small, fast model of your choice:

completion:
  enabled: true
  provider: ""      # a name under agent.providers; empty = agent.default_provider
  model: ""         # a small, fast model; empty = off
  delay: 300ms      # pause in typing before asking
  max_tokens: 256