Preliminary flycheck support for Clojure using Cider and Eastwood

clj-fly

;;; clj-fly.el --- Flycheck: Clojure support    -*- lexical-binding: t; -*-
;;; Commentary:
;;; So far, this only invokes eastwood.  It works best if flycheck-pos-tip is used, so as not to clash with Cider doc messages.

;;; Code:

(require 'cider-client)
(require 'flycheck)

(defun parse-eastwood (s)
  "Parse an output line from eastwood: S."
  (let ((r "^\\([^[:space:]]+\\)\\:\\([[:digit:]]+\\)\\:\\([[:digit:]]+\\)\\:[[:space:]]*\\(.*\\)")
	;(s  "bar:foo:bleh whee")
	)
    (if (string-match r s)
	;;(mapcar (lambda (n) (match-string n s)) '(1 2 3 4))
	(list
	 (match-string 1 s)                     ;; file
	 (string-to-number (match-string 2 s))  ;; line
	 (string-to-number (match-string 3 s))  ;; col
	 (match-string 4 s)                     ;; msg
	 ))))

(defun flycheck-clj-cider-start (checker callback)
  "Begin flychecking, with CHECKER and CALLBACK."
  (let* ((buffer (current-buffer))
	 (ns     (cider-current-ns))
	 (cmd    (format "(do (require 'eastwood.lint)(eastwood.lint/eastwood {:source-paths [\"src\"] :namespaces ['%s] } ))"
			 ns))
	 (errors      ()))
    ;;(message "here i am in start: %s" cmd)
    (cider-eval cmd
     (nrepl-make-response-handler
      buffer
      (lambda (_buffer _value)
	;;(message (prin1-to-string errors))
	(funcall callback 'finished errors))
      (lambda (_buffer out)
	(mapc (lambda (w) (pcase-let* ((`(,file ,line ,column ,msg) w))
			      (push
			       (flycheck-error-new-at line column 'error msg
						      :checker checker
						      :buffer buffer
						      :filename (buffer-file-name buffer)
						      )
			       errors)))
		(delq nil (mapcar 'parse-eastwood (split-string out "\n"))))
	)
      (lambda (_buffer err))
      '())
     ))
  )


(flycheck-define-generic-checker 'clojure-cider-checker
  "A syntax checker for Clojure using Cider"
  :start #'flycheck-clj-cider-start
  :modes '(clojure-mode)
  )

(add-to-list 'flycheck-checkers 'clojure-cider-checker)

(provide 'clj-fly)
;;; clj-fly.el ends here