Help.hs

module SMR.CLI.Help where


helpCommands :: String
helpCommands
 = unlines $
 [ "  :quit,:q        Quit the REPL."
 , "  :help           Show this Help page."
 , "  :grammar        Show the language grammar."
 , "  :prims          Show the list of available primitives."
 , "  :reload,:r      Reload the current source files."
 , "  :decls  NAMES?  Show named declarations, or all decls if no names given."
 , "  :parse  EXP     Parse an expression and print it back."
 , "  :push   EXP     Push down substitutions in an expression."
 , "  :step   EXP     Single step evaluate an expression."
 , "  :steps  EXP     Multi-step evaluate an expression."
 , "  :trace  EXP     Multi-step evaluate an expression, showing intermediate states." ]


helpGrammar :: String
helpGrammar
 = unlines $
 [ "  Decl  ::= '@' Name Param* '=' Exp ';'    (Macro declaration)"
 , ""
 , "  Exp   ::=  Ref                           (External reference)"
 , "         |   Key Exp                       (Keyword  application)"
 , "         |   Exp Exp+                      (Function application)"
 , "         |   Name ('^' Nat)?               (Variable with lifting specifier)"
 , "         |   '\\' Param+ '.' Exp            (Function abstraction)"
 , "         |   Train      '.' Exp            (Substitution train)"
 , ""
 , "  Ref   ::= '@' Name                       (Macro reference)"
 , "         |  '%' Name                       (Symbol reference)"
 , "         |  '#' Name                       (Primitive reference)"
 , "         |  '?' Nat                        (Nominal reference)"
 , ""
 , "  Key   ::= '##tag'                        (Tag an expression)"
 , "         |  '##seq'                        (Sequence evaluation)"
 , "         |  '##box'                        (Box an expression, delaying evaluation)"
 , "         |  '##run'                        (Run an expression, forcing  evaluation)"
 , ""
 , "  Param ::= Name                           (Call-by-value parameter)"
 , "         |  '!' Name                       (Explicitly call-by-value parameter)"
 , "         |  '~' Name                       (Explicitly call-by-name  parameter)"
 , ""
 , "  Train ::= Car+                           (Substitution train)"
 , ""
 , "  Car   ::= '['  Bind,* ']'                (Simultaneous substitution)"
 , "         |  '[[' Bind,* ']]'               (Recursive substitution)"
 , "         |  '{'  Bump,* '}'                (Lifting specifier)"
 , ""
 , "  Bind  ::= Name ('^' Nat)? '=' Exp        (Variable substitution binding)"
 , "         |  '?' Nat         '=' Exp        (Nominal  substitution binding)"
 , ""
 , "  Bump  ::= Name ('^' Nat)? ':' Nat        (Lifting bump)"
 ]