[Haskell-beginners] annoying precedence of unary negate

[John M. Dlugosz]

On 4/27/2014 11:24 PM, Magnus Therning wrote:
> On Sun, Apr 27, 2014 at 10:59:27PM -0500, John M. Dlugosz wrote:
>>
>
> It most likely  sees it as the binary minus rather than the unary minus.
>

That's what I thought.

  Couldn't match expected type `Picture'
              with actual type `Float -> Picture -> Picture'
  In the expression: translate - 50 0 $ color green (Circle 50)
  In the first argument of `Pictures', namely
    `[Circle 100, translate - 50 0 $ color green (Circle 50),
      scale 200 200 $ color red $ (Pictures $ take 20 chain1), testcirc]'
  In the expression:
    Pictures
      [Circle 100, translate - 50 0 $ color green (Circle 50),
       scale 200 200 $ color red $ (Pictures $ take 20 chain1), testcirc]

But what is the error message telling me?
Given that infix is done after adjacency application, it should parse as:
	((translate - (50 0) ) $ (color (green (Circle 50))))

Left of the $, that is the parse tree

	subtract+
		|
		+ translate
		|
		+ apply+
		       |
		       + 50
		       |
		       + 0

I think it would complain that 50 isn't a function, or the first argument of subtract is 
not a Num but a function
	translate :: Float -> Float -> Picture -> Picture,
or that the argument of translate isn't a Float but something it can't make sense of.
Why is it looking for a Picture?  Where is it getting Float->Picture->Picture (seems to be 
a curried translate?  But the next token is not something it would like so how can it find 
a first argument?)

Understanding the compiler's errors is a skill I want to learn, as well as shake out my 
understanding of what's really going on.

Thanks,
—John