7.9.3.1 Readline Port ¶

Function: readline-port ¶

Return a buffered input port (see Buffered Input) which calls the readline function above to get input. This port can be used with all the usual reading functions (read, read-char, etc), and the user gets the interactive editing features of readline.

There’s only a single readline port created. readline-port creates it when first called, and on subsequent calls just returns what it previously made.

Function: activate-readline ¶

If the current-input-port is a terminal (see isatty?) then enable readline for all reading from current-input-port (see Default Ports for Input, Output and Errors) and enable readline features in the interactive REPL (see Using the Guile REPL).

(activate-readline)
(read-char)

activate-readline enables readline on current-input-port simply by a set-current-input-port to the readline-port above. An application can do that directly if the extra REPL features that activate-readline adds are not wanted.

Function: set-readline-prompt! prompt1 [prompt2] ¶

Set the prompt string to print when reading input. This is used when reading through readline-port, and is also the default prompt for the readline function above.

prompt1 is the initial prompt shown. If a user might enter an expression across multiple lines, then prompt2 is a different prompt to show further input required. In the Guile REPL for instance this is an ellipsis (‘...’).

See set-buffered-input-continuation?! (see Buffered Input) for an application to indicate the boundaries of logical expressions (assuming of course an application has such a notion).

7.9.3.2 Completion ¶

Function: with-readline-completion-function completer thunk ¶

Call (thunk) with completer as the readline tab completion function to be used in any readline calls within that thunk. completer can be #f for no completion.

completer will be called as (completer text state), as described in (see How Completing Works in GNU Readline Library). text is a partial word to be completed, and each completer call should return a possible completion string or #f when no more. state is #f for the first call asking about a new text then #t while getting further completions of that text.

Here’s an example completer for user login names from the password file (see User Information), much like readline’s own rl_username_completion_function,

(define (username-completer-function text state)
  (if (not state)
      (setpwent))  ;; new, go to start of database
  (let more ((pw (getpwent)))
    (if pw
        (if (string-prefix? text (passwd:name pw))
            (passwd:name pw)     ;; this name matches, return it
            (more (getpwent)))   ;; doesn't match, look at next
        (begin
          ;; end of database, close it and return #f
          (endpwent)
          #f))))

Function: apropos-completion-function text state ¶

A completion function offering completions for Guile functions and variables (all defines). This is the default completion function.

Function: filename-completion-function text state ¶

A completion function offering filename completions. This is readline’s rl_filename_completion_function (see Completion Functions in GNU Readline Library).

Function: make-completion-function string-list ¶

Return a completion function which offers completions from the possibilities in string-list. Matching is case-sensitive.