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%Syntactic sugar examples %
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local X A B in
   A = "George"
   B = 25
   X = person(name:A age:B)
end

local X = person(name:"George" age:25) in skip end
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local T in
   local A B C D in
      T = tree(key:A left:B right:C value:D)
      A = 1
      B = 2
      C = 3
      D = 4
   end
end

local T in
   local tree(key:A left:B right:C value:D) = T in
      A = 1
      B = 2
      C = 3
      D = 4
   end
end

local A B C D T = tree(key:A left:B right:C value:D) in
   A = 1
   B = 2
   C = 3
   D = 4
end

%Exercise 1(Also in last slide of the lecture)
%Here is another attempt at a construct equivalent to the above. Will it work? Why or why not?
%local T = tree(key:A left:B right:C value:D) in
%   A = 1
%   B = 2
%   C = 3
%   D = 4
%end
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local T in
   local tree(key:A left:B right:C value:D)=T in A = 1 B = 2 C = 3 D = 4 end
end

local T in
   local A B C D in
      {Label T} = tree
      T.key = A
      T.left=B
      T.right=C
      T.value=D
      A = 1
      B = 2
      C = 3
      D = 4
   end
end
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%Exercise 2.1 (Also in the last slide of the lecture)
%Here is a construct that uses some syntactic sugar:
%local T in
%   local tree(left:A right:B) = T in <stmt>
%end

%Here is an attempt to write the same construct using only the kernel language:
%local T in
%   local A B in
%      {Label T} = tree
%      T.right = B
%      T.left = A
%      <stmt>
%   end
%end

%Are the above constructs always equivalent? Can you find a case when they are not? If not, how will you justify your belief that they are equivalent?

%Exercise 2.2 (Also in the last slide of the lecture)
%Now suppose that A and B are predefined variables and Func1 is a predefined one argument function
%Here is a construct that uses some syntactic sugar: 
%local T  in
%      tree(left:{Func1 A} right:{Func1 B}) = T 
%end

%Here is an attempt to write the same construct using only the kernel language:
%local T in
%   {Label T} = tree
%   T.right = {Func1 B}
%   T.left = {Func1 A}
%end

%Are the above constructs always equivalent?
%How will your answer change if you are told that neither A nor B is unbound?
%How will your answer change if you are told that neither A nor B is unbound, and Func1 never throws an exception?
%How will your answer change if you are told that neither A nor B is unbound, and Func1 is a lamda combinator?
%How will your answer change if you are told that neither A nor B is unbound, and Func1 never throws an exception, and Func1 is a lambda combinator?
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%Extracting values from a compound data structure %
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local T A in
   T = tree(key:"seif" age:48 profession:"professor")
   tree(key:A ...) = T
   {Browse A}  
end
%Note : The browser will display a list of ASCII values. To view that as a string, click on Options, Representation and then String
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%%%%%%%%%%%%%%%%%%%%%%%%
%Avoiding Memory Leaks %
%%%%%%%%%%%%%%%%%%%%%%%%
local fun {Sum X L1 L} 
	 case L1 of Y|L2
	 then {Sum X+Y L2 L}
	 else X
	 end
      end
in skip
end

local fun {Sum X L1}
	 case L1 of Y|L2 then {Sum X+Y L2}
	 else X
	 end
      end
in skip
end
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