Issues with some example expressions

[jvstinian]

Running the "SVG Chart" example from the side panel results in an error:

:278:1: error: [GHC-58481]
parse error (possibly incorrect indentation or mismatched brackets)

It looks like the block is being interpreted as an expression, so this can be fixed by inserting in to complete the let expression, or alternatively by wrapping the entire block in a do statement.

It looks like a similar issue might affect other examples such as "Fibonacci", "Map & Filter", and "QuickCheck".

[mchav]

That's probably a parsing error: if you include a space between the text and the display it works:

let bars = zip ["Mon","Tue","Wed","Thu","Fri"] [40,65,30,80,55 :: Int]
    bar (label, h) i = unlines
      [ "<rect x='" ++ show (i*60+10) ++ "' y='" ++ show (100-h) ++ "' width='40' height='" ++ show h ++ "' fill='#89b4fa' rx='4'/>"
      , "<text x='" ++ show (i*60+30) ++ "' y='115' text-anchor='middle' fill='#cdd6f4' font-size='11'>" ++ label ++ "</text>" ]
    svg = "<svg width='320' height='130' style='background:#1e1e2e;padding:8px'>" ++ concatMap (\(b,i) -> bar b i) (zip bars [0..]) ++ "</svg>"

displaySvg svg

[jvstinian]

Adding a space does result in a successful calculation. Interestingly, the List Comprehension example

let triples = [(a,b,c) | c <- [1..20], b <- [1..c], a <- [1..b], a*a + b*b == c*c]
print triples

works without adjustment, but the Map & Filter example

let xs = [1..20]
print $ filter even $ map (^2) xs

requires an additional empty line to run successfully.

[mchav]

I'll have to add more test cases to script HS. And honestly it should really be a full blown parser.