picat-mode.el

;; Adapted from https://github.com/rurban/picat-lang/blob/master/picat-mode.el
;; mostly the same but this one works..
;;
(eval-when-compile
  (require 'generic)
  (require 'font-lock)
  (require 'regexp-opt))


(defmacro picat-match-symbol (&rest symbols)
  "Convert a word-list into a font-lock regexp."
  (concat "\\_<" (regexp-opt symbols t) "\\_>"))

(setf picat-keywords '("in" "not" "fail" "pass" "true" "false"))

;;;###autoload
(define-generic-mode picat-mode
  '("%" ("/*" . "*/"))     		   ;comments
  picat-keywords
  `(                                       ;font-lock-list
    ;; block delimiters
    ("[.:]" . font-lock-preprocessor-face)
    ;; arrays, structs
    ("\\[\\|\\]\\|\{\\|\}" . font-lock-warning-face)
    (,(concat
       ;; one-char operators
       "[,()|?=+~*%<>=!&^-]"
       ;; multi-char operators
       "\\|\\("
       "\\+\\+\\|--\\|\\*\\*\\|<<\\|>>\\|<=\\|>=\\|==\\|!=\\|=>\\|<=>\\|&&\\|||"
       "\\)")
     . font-lock-builtin-face)
    ;; slash is magical
    ("\\(/\\) " 1 font-lock-builtin-face)
    ;; numeric constants
    ("\\_<[0-9]+\\(\\.[0-9]*\\)?\\([Ee][+-]?[0-9]+\\)?\\_>" . font-lock-constant-face)
    ("0x[a-fA-F0-9]+" . font-lock-constant-face)
    ;; attributes
    ;("/\\(?:\\sw\\|\\s_\\)+\\_>" . font-lock-variable-name-face)
    ;; control constructs
    (,(picat-match-symbol
       "if" "then" "elseif" "else" "end" "loop" "while" "in" "foreach" "..")
     . font-lock-keyword-face)
    ;; core functions (XXX some overlap with operators)
    (,(picat-match-symbol
       "%" "*" "**" "+" "+" "-" "/" "<<" ">>" "abs" "append" "apply" "arity"
       "attr" "call" "chr" "clone" "close" "code" "compile"
       "eval" "exit" "first" "float" "here" "integer"
       "join" "last" "length" "import" "length" "list" "load"
       "name" "new_struct" "new_array" "new_map"
       "number" "ord" "pop" "print" "println" "push" "put" "rand" "read"
       "remove" "reverse" "self" "send" "slice" "sqrt" "srand" "string"
       "text" "to" "tree" "write" "~") . font-lock-builtin-face)
    )
  '("\\.pi$")                           ;file extension
  '((lambda ()                          ;other setup work
      (modify-syntax-entry ?' "\"")
      (modify-syntax-entry ?: "(.")
      (modify-syntax-entry ?\. "):"))
    ;; Setup extremely primitive indentation (less annoying than default 'indent-relative).
    (lambda ()
      (setq-default indent-tabs-mode nil)
      (setq-default tab-width 4)
      (setq indent-line-function 'insert-tab)
      )
    )
  "Major mode for editing picat-lang."
)

(provide 'picat-mode)

If you use spacemacs, you probably will have trouble with adding local packages easily (this is not on melpa). I get around this by adding the following to my init.el,

  (use-package picat-mode
    :load-path "~/.spacemacs.d/local-packages/picat-mode"
    )