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-----------------------------------------------------------------------------
--
-- Module : Directive
-- Copyright :
-- License : MIT
--
-- Maintainer :
-- Stability : experimental
-- Portability :
--
-- |
-- Directives for PSCI.
--
-----------------------------------------------------------------------------
module Directive where
import Data.Maybe (fromJust, listToMaybe)
import Data.List (isPrefixOf)
import Data.Tuple (swap)
import Types
-- |
-- List of all avaliable directives.
--
directives :: [Directive]
directives = map fst directiveStrings
-- |
-- A mapping of directives to the different strings that can be used to invoke
-- them.
--
directiveStrings :: [(Directive, [String])]
directiveStrings =
[ (Help , ["?", "help"])
, (Quit , ["quit"])
, (Reset , ["reset"])
, (Browse , ["browse"])
, (Load , ["load", "module"])
, (Type , ["type"])
, (Kind , ["kind"])
, (Show , ["show"])
]
-- |
-- Like directiveStrings, but the other way around.
--
directiveStrings' :: [(String, Directive)]
directiveStrings' = concatMap go directiveStrings
where
go (dir, strs) = map (\s -> (s, dir)) strs
-- |
-- List of all directive strings.
--
strings :: [String]
strings = concatMap snd directiveStrings
-- |
-- Returns all possible string representations of a directive.
--
stringsFor :: Directive -> [String]
stringsFor d = fromJust (lookup d directiveStrings)
-- |
-- Returns the default string representation of a directive.
--
stringFor :: Directive -> String
stringFor = head . stringsFor
-- |
-- Returns the list of directives which could be expanded from the string
-- argument, together with the string alias that matched.
--
directivesFor' :: String -> [(Directive, String)]
directivesFor' str = go directiveStrings'
where
go = map swap . filter ((str `isPrefixOf`) . fst)
directivesFor :: String -> [Directive]
directivesFor = map fst . directivesFor'
directiveStringsFor :: String -> [String]
directiveStringsFor = map snd . directivesFor'
parseDirective :: String -> Maybe Directive
parseDirective = listToMaybe . directivesFor
-- |
-- True if the given directive takes an argument, false otherwise.
hasArgument :: Directive -> Bool
hasArgument Help = False
hasArgument Quit = False
hasArgument Reset = False
hasArgument _ = True
-- |
-- The help menu.
--
help :: [(Directive, String, String)]
help =
[ (Help, "", "Show this help menu")
, (Quit, "", "Quit PSCi")
, (Reset, "", "Discard all imported modules and declared bindings")
, (Browse, "<module>", "See all functions in <module>")
, (Load, "<file>", "Load <file> for importing")
, (Type, "<expr>", "Show the type of <expr>")
, (Kind, "<type>", "Show the kind of <type>")
, (Show, "import", "Show all imported modules")
, (Show, "loaded", "Show all loaded modules")
]
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