REPL

REPL

The REPL in swank.nvim is a read-only output buffer that displays all output from the Swank server: evaluation results, format t output, warnings, and interactive prompts.

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Opening the REPL

The REPL window opens automatically whenever new output arrives from the server. You can also toggle it manually:

<Leader>rw

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Layout

Three layouts are available: vertical split (right), horizontal split (bottom), and floating window.

"auto" (default)

The plugin picks the best layout based on your terminal dimensions:

1. Vertical split (right) — if the configured size gives the REPL at least 80 columns. At the default 45%, this requires ~178 terminal columns.
2. Horizontal split (bottom) — if the vertical split would be too narrow but a horizontal split gives at least 12 rows.
3. Float — if the terminal is too small for either split.

Explicit layouts

require("swank").setup({
  ui = {
    repl = {
      position = "right",   -- always vertical split
      -- position = "bottom", -- always horizontal split
      -- position = "float",  -- always floating
      size     = 0.45,
    }
  }
})

Size

size controls the width (for "right") or height (for "bottom") of the REPL window.

Value	Meaning
0.45	45% of the relevant editor dimension (default)
0.33	33% (one-third)
0.25	25%
80	exactly 80 columns or rows

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Switching packages

<Leader>lp

Prompts for a package name and tells the Swank server to switch the active evaluation context to that package. This is a connection-level setting and is available from any Lisp buffer, not just the REPL.

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Output types

The REPL buffer shows output from multiple Swank event types:

Swank event	What you see
:write-string	Raw output from (format t ...), (print ...), etc.
:presentation-start / :presentation-end	Result presentations from eval
:read-string	Interactive read prompt (e.g. (read))
:debug-activate	Debugger entered — shown inline before SLDB window

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Interacting with the REPL buffer

The REPL buffer (swank://repl) is normally read-only. To send an expression to the server, use <Leader>ei (interactive eval with prompt) or the eval keymaps from a Lisp source buffer.

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Troubleshooting

REPL doesn't open automatically

Check that require("swank").attach(bufnr) is being called for your Lisp buffers. The auto-open is triggered from ui/repl.lua:M.append(), which is only called if the client is wired up.

REPL opens in the wrong place

Explicitly set position to "right", "bottom", or "float" in your config to bypass the auto-detection logic.

Startup noise from SBCL

swank.nvim silently discards stderr from the sbcl process during normal startup. The Swank contrib compilation STYLE-WARNINGs you see in a terminal are suppressed. Stderr is only surfaced as a notification if sbcl exits with a non-zero exit code.