sml

I am trying to get the product of a tree by using the fold function so far this is what I have. I am confused on how to use the fold method while transversing the tree datatype 'a bin_tree = Leaf of 'a | Node of 'a bin_tree * 'a bin_tree fun treefold g z Empty = z | treefold g z (Node (l, x, r)) = g(x, g(treefold g z l, treefold g z r) First, some pointers about what isn't quite in order in your attempt. The base case of your treefold function matches against the value constructor Empty , but you don't define the bin_tree datatype to include an Empty value constructor. As John Coleman points

Are there standard sorting functions in SML? The documentation on the Internet is so scarce I couldn't find any. Jesper.Reenberg Rachel is only partly right. It is true that there is no sorting functionality defined in the SML Basis Library, however most implementations extend the basis library and add extra functionality. As such MosML has both an ArraySort and a Listsort module, and SML/NJ has a LIST_SORT signature with a ListMergeSort implementation. It also features some other sorting features on arrays as MosML. See the toc of the SML/NJ Library Manual, for a full list. As Jesper Reenberg

I've been given the following code and I've been asked to determine the type. exception Break; fn f => fn a => fn b => (f(raise Break) handle Break => if (f a) then a else raise Break) handle Break => if not(f a) then a else b; I know that this function takes in f, a and b and outputs a in all instances so it must be equivelant to: fn f => fn a => fn b => a which has the type: 'a -> 'b -> 'c -> 'b because 'if( f a)' we can derive that 'a must be a function that takes in type 'b and outputs a boolean otherwise it wouldn't work. ('b->bool) -> 'b -> 'c -> 'b re done so 'a is the beginning: ('a-

I am suddenly in a recursive language class (sml) and recursion is not yet physically sensible for me. I'm thinking about the way a floor of square tiles is sometimes a model or metaphor for integer multiplication, or Cuisenaire Rods are a model or analogue for addition and subtraction. Does anyone have any such models you could share? Imagine you're a real life magician, and can make a copy of yourself. You create your double a step closer to the goal and give him (or her) the same orders as you were given. Your double does the same to his copy. He's a magician too, you see. When the final

I'm trying to get SML/NJ to print out a result at the top level without putting # signs everywhere. According to some old docs (and a post to this newsgroup on 2001), it should be possible to use Compiler.Control.Print.printDepth However, on SML/NJ version 110.7, this just gives an error: - Compiler.Control.Print.printDepth := 100; stdIn:1.1-30.8 Error: unbound structure: Control in path Compiler.Control.Print.printDepth You might wan't to be more precise in the future. You could for example give some sample output and a link to where you found the above. If I understand your problem correct,

I start to learn Standard ML, and now I try to use Standard ML of New Jersey compiler. Now I can use interactive loop, but how I can compile source file to standalone executable? In C, for example, one can just write $ gcc hello_world.c -o helloworld and then run helloworld binary. I read documentation for SML NJ Compilation Manager, but it don`t have any clear examples. Also, is there another SML compiler (which allow standalone binary creating) available? Both MosML and MLton also have the posibility to create standalone binary files. MosML through mosmlc command and MLton through the mlton

In SML (a functional programming language that I learned before Python), I can do the following: val x = 3; fun f() = x; f(); >>> 3 val x = 7; f(); >>> 3 In Python, however, the first call will give 3 and the second one will give 7. x = 3 def f(): return x f() >>> 3 x = 7 f() >>> 7 How do I bind the value of a variable to a function in Python? You can use a keyword argument: x = 3 def f( x=x ): return x x = 7 f() # 3 Keyword arguments are assigned when the function is created . Other variables are looked up in the function's scope when the function is run . (If they're not found in the

Suppose I have a list in sml which is very big then sml shows a few of the entries and then starts showing # character. Could someone tell me how could I view the whole list? Assuming this is SML/NJ you could use printLength , printDepth and friends from the Control.Print structure. The following are a snippet from the documentation of the Control.Print structure: printDepth The depth of nesting of recursive data structure at which ellipsis begins. printLength The length of lists at which ellipsis begins. stringDepth The length of strings at which ellipsis begins. Thus for example we can