Add lambda icons and lambda regions.

app/Icons.hs

@@ -10,7 +10,9 @@ module Icons
     connectPorts,
     connectIconToPort,
     connectIconToIcon,
-    textBox
+    textBox,
+    enclosure,
+    lambdaRegion
     ) where
 
 import Diagrams.Prelude
@@ -78,11 +80,10 @@ apply0Dia = (resultCircle ||| apply0Line ||| apply0Triangle) <> makePortDiagrams
 apply0Icon :: Icon B
 apply0Icon = Icon apply0Dia verts
 
+makePort x = mempty # named (PortName x)
+
 makePortDiagrams points =
   atPoints points (map makePort [0,1..])
-  where
-    --makePort x = (circle 0.2 # fc green) # named (PortName x)
-    makePort x = mempty # named (PortName x)
 
 verts = map p2 [
   (circleRadius + apply0LineWidth + triangleWidth, 0),
@@ -97,11 +98,30 @@ verts = map p2 [
 textBoxFontSize = 1
 monoLetterWidthToHeightFraction = 0.6
 textBoxHeightFactor = 1.1
+
 textBox :: String -> Diagram B
-textBox t =
-  text t # fc white # font "freemono" # bold # fontSize (local textBoxFontSize)
-  <> rect rectangleWidth (textBoxFontSize * textBoxHeightFactor) # lc white
+textBox = coloredTextBox white $ opaque white
+
+-- Since the normal SVG text has no size, some hackery is needed to determine
+-- the size of the text's bounding box.
+coloredTextBox textColor boxColor t =
+  text t # fc textColor # font "freemono" # bold # fontSize (local textBoxFontSize)
+  <> rect rectangleWidth (textBoxFontSize * textBoxHeightFactor) # lcA boxColor
   where
     rectangleWidth = textBoxFontSize * monoLetterWidthToHeightFraction
       * fromIntegral (length t)
       + (textBoxFontSize * 0.2)
+
+-- ENCLOSING REGION --
+enclosure dia = dia <> boundingRect (dia # frame 0.5) # lc red # lwG defaultLineWidth
+
+-- LAMBDA ICON --
+-- Don't use === here to put the port under the text box since mempty will stay
+-- at the origin of the text box.
+lambdaIcon x = coloredTextBox lime transparent "λ" # alignB <> makePort x
+
+-- LAMBDA REGION --
+
+-- | lambdaRegion takes as an argument the numbers of parameters to the lambda,
+-- and draws the diagram inside a region with the lambda icons on top.
+lambdaRegion n dia = hsep 0.4 (take n (map lambdaIcon [0,1..])) # center === enclosure dia

app/Main.hs

@@ -19,7 +19,13 @@ fromAtoB = ex3 # connectPorts "A" (PortName 0) "B" (PortName 2)
 ex4 = apply0A ||| textBox "hello world" === textBox "1" === textBox "gpq" === textBox ['A'..'Z']
 ex5 = textBox "baz" # named "baz"||| hrule 1 ||| fromAtoB ||| hrule 1 ||| textBox "foo" # named "foo" === vrule 1 === textBox "bar" # named "bar"
 ex6 = ex5 # connectIconToPort "baz" "A" (PortName 2) # connectIconToPort "foo" "B" (PortName 0)
-  # connectIconToPort "bar" "B" (PortName 3)
+  # connectIconToPort "bar" "B" (PortName 3) # centerXY
+ex7 = ex6 # center # showOrigin # showEnvelope
+--ex8 = ex6 <> boundingRect (ex6 # frame 0.5) # lc blue # lw veryThick
+ex8 = enclosure ex6
+ex9 = lambdaRegion 3 ex6 # nameDiagram "lam0"
+ex10 = ex9 # connectPorts ("lam0" .> "A") (PortName 1) "lam0" (PortName 0)
+  # connectPorts ("lam0" .> "B") (PortName 1) "lam0" (PortName 2)
 
 main :: IO ()
-main = mainWith (ex6 # frame 0.1 # bg black)
+main = mainWith (ex10 # bgFrame 0.1 black)

notes.txt

@@ -1,9 +1,10 @@
 to run:
 Using Atom, in a terminal run
-stack exec glance-exe -- -l -s app/Main.hs -o circle.svg
+cd app
+stack exec glance-exe -- -l -s Main.hs -o ../output.svg
 
 or if that does not work
 
-stack build  --exec "glance-exe -o circle.svg -w 500"
+stack build  --exec "glance-exe -o output.svg -w 500"
 
 View circle.svg with svg-preview plug-in.