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title author tags abstract
A Lightning Talk with GHCJS
Luite Stegeman
Haskell
functional programming
JavaScript
web
GHCJS
Haskell Symposium 2015

fibs = 0 : 1 : zipWith (+) fibs (tail fibs)


## Run Haskell

```{.haskell}
start ref = staticText ref (take 30 (show fibs) ++ "...")
---
fibs = 0 : 1 : zipWith (+) fibs (tail fibs)

Run Haskell

start ref = dynamicText ref "10" (show . (fibs!!) . read)
---
fibs = 0 : 1 : zipWith (+) fibs (tail fibs)

Run Haskell

start ref = dynamicText ref "10" (show . (fibs!!) . read)
---
fibs = 0 : 1 : zipWith (+) fibs (tail fibs)

start ref = staticDiagram ref 600 300 (tournament 5)

node :: Int -> Diagram Canvas
node n = circle 0.2 # fc green # named n

arrowOpts = with & gaps       .~ small
                 & headLength .~ local 0.15

tournament :: Int -> Diagram Canvas
tournament n = atPoints (trailVertices $ regPoly n 1) (map node [1..n])
  # applyAll [connectOutside' arrowOpts j k | j <- [1 .. n-1], k <- [j+1 .. n]]

start ref = dynamicDiagram ref 600 300 "5" (tournament . read)

node :: Int -> Diagram Canvas
node n = circle 0.2 # fc green # named n

arrowOpts = with & gaps       .~ small
                 & headLength .~ local 0.15

tournament :: Int -> Diagram Canvas
tournament n = atPoints (trailVertices $ regPoly n 1) (map node [1..n])
  # applyAll [connectOutside' arrowOpts j k | j <- [1 .. n-1], k <- [j+1 .. n]]

start ref = dynamicDiagram ref 600 300 "0.45" (example . read)
---
pts = map p2 [(0,0), (1,1), (2,1), (3,0), (3.5,0)]

spline :: Located (Trail V2 Double)
spline = cubicSpline False pts

example :: Double -> Diagram Canvas
example param = frame 0.5 $
  strokeLocTrail spline
  <> mconcat
     [ tangentLine
     , baselineText "tangent" # translate tangentVector
     , normalLine
     , topLeftText "normal" # translate normalVector
     , rightAngleSquare
     ] # moveTo pt # fontSize large
  where
    pt = atParam spline param
    tangentVector = tangentAtParam spline param
    normalVector = normalAtParam spline param
    symmetricLine v = fromOffsets [2 *^ v] # center
    tangentLine = symmetricLine tangentVector
    normalLine = symmetricLine normalVector
    rightAngleSquare = square 0.1 # alignBL # rotate (signedAngleBetween tangentVector unitX)


start ref = 
  let w   = 600
      h   = 300
      sq  = square 1 # scaleX w # scaleY h # fc green
      cir = circle 10 # fc blue 
  in mouseDiagram ref 600 300 $ \x y ->
       translate (r2 (w*x-w/2-5,5+h/2-h*y)) cir `atop` sq

start ref = mouseDiagram ref 600 300 (\x _y -> example x)
---
pts = map p2 [(0,0), (1,1), (2,1), (3,0), (3.5,0)]

spline :: Located (Trail V2 Double)
spline = cubicSpline False pts

example :: Double -> Diagram Canvas
example param = frame 0.5 $
  strokeLocTrail spline
  <> mconcat
     [ tangentLine
     , baselineText "tangent" # translate tangentVector
     , normalLine
     , topLeftText "normal" # translate normalVector
     , rightAngleSquare
     ] # moveTo pt # fontSize large
  where
    pt = atParam spline param
    tangentVector = tangentAtParam spline param
    normalVector = normalAtParam spline param
    symmetricLine v = fromOffsets [2 *^ v] # center
    tangentLine = symmetricLine tangentVector
    normalLine = symmetricLine normalVector
    rightAngleSquare = square 0.1 # alignBL # rotate (signedAngleBetween tangentVector unitX)


import Diagrams.TwoD.Factorization

example = fdGridList 4 # center # pad 1.05

start ref = staticDiagram ref 600 300 example

import Diagrams.TwoD.Factorization

start ref = mouseDiagram ref 600 300 $ \x _ ->
  factorDiagram (1 + floor (50 * x))

import Diagrams.TwoD.Apollonian

start ref = mouseDiagram ref 600 300 $ \x y ->
  let a = 1 + 6 * x
      b = 5 - 4 * y
  in apollonianGasket 0.1 2 a b # centerXY # pad 1.1

Credits

Brent Yorgey

  • Factorization Diagrams
  • Tournament Graph
  • Apollonian Gasket

Pontus Granström

  • Tangent and Normal

Conclusion

Conclusion

Install GHCJS with GHC 7.10.2 and help test improved-base

$ cabal install http://ghcjs.luite.com/improved-base.tar.gz
$ ghcjs-boot

Code for the slides will be available from my Github

http://github.com/luite/hs15-talk