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81 lines
2.0 KiB
Haskell
81 lines
2.0 KiB
Haskell
module MiniMiniLogoSem where
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import MiniMiniLogo
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import Render
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--
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-- * Semantics of MiniMiniLogo
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--
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-- NOTE:
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-- * MiniMiniLogo.hs defines the abstract syntax of MiniMiniLogo and some
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-- functions for generating MiniMiniLogo programs. It contains the type
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-- definitions for Mode, Cmd, and Prog.
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-- * Render.hs contains code for rendering the output of a MiniMiniLogo
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-- program in HTML5. It contains the types definitions for Point and Line.
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-- | A type to represent the current state of the pen.
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type State = (Mode,Point)
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-- | The initial state of the pen.
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start :: State
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start = (Up,(0,0))
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-- | A function that renders the image to HTML. Only works after you have
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-- implemented `prog`. Applying `draw` to a MiniMiniLogo program will
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-- produce an HTML file named MiniMiniLogo.html, which you can load in
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-- your browswer to view the rendered image.
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draw :: Prog -> IO ()
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draw p = let (_,ls) = prog p start in toHTML ls
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-- Semantic domains:
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-- * Cmd: State -> (State, Maybe Line)
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-- * Prog: State -> (State, [Line])
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-- | Semantic function for Cmd.
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--
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-- >>> cmd (Pen Down) (Up,(2,3))
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-- ((Down,(2,3)),Nothing)
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--
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-- >>> cmd (Pen Up) (Down,(2,3))
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-- ((Up,(2,3)),Nothing)
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--
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-- >>> cmd (Move 4 5) (Up,(2,3))
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-- ((Up,(4,5)),Nothing)
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--
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-- >>> cmd (Move 4 5) (Down,(2,3))
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-- ((Down,(4,5)),Just ((2,3),(4,5)))
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--
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-- Done
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cmd :: Cmd -> State -> (State, Maybe Line)
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cmd (Pen s) (m, p) = ((s, p), Nothing)
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cmd (Move x1 y1) (s, (x2, y2)) = case s of
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Down -> ((s,(x1, y1)),Just ((x2,y2),(x1,y1)))
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Up -> ((s,(x1, y1)),Nothing)
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-- | Semantic function for Prog.
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--
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-- >>> prog (nix 10 10 5 7) start
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-- ((Down,(15,10)),[((10,10),(15,17)),((10,17),(15,10))])
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--
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-- >>> prog (steps 2 0 0) start
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-- ((Down,(2,2)),[((0,0),(0,1)),((0,1),(1,1)),((1,1),(1,2)),((1,2),(2,2))])
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--
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--
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prog :: Prog -> State -> (State, [Line])
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prog p (s, (x,y)) = ((s,(x,y)), prog p)
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--
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-- * Extra credit
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--
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-- | This should be a MiniMiniLogo program that draws an amazing picture.
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-- Add as many helper functions as you want.
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amazing :: Prog
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amazing = undefined
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