sml

I'm coding in SML for an assignment and I've done a few practice problems and I feel like I'm missing something- I feel like I'm using too many case statements. Here's what I'm doing and the problem statements for what I'm having trouble with.: Write a function all_except_option, which takes a string and a string list. Return NONE if the string is not in the list, else return SOME lst where lst is like the argument list except the string is not in it. fun all_except_option(str : string, lst : string list) = case lst of [] => NONE | x::xs => case same_string(x, str) of true => SOME xs | false =

I have the function below and it works: (fn x => x * 2) 2; but this one doesn't work: (fn x y => x + y ) 2 3; Can anyone tell me why? Or give me some hint to get it to work? (fn x => fn y => x+y) 2 3; works. fn simply doesn't have the same syntactic sugar to define curried functions that fun has. In Standard ML, a function can have only one argument , so use (fn (x,y) => x + y) (2,3) and the type is fn: int * int -> int in this time (x,y) and (2,3) is a list structure, The answers posted above are correct. SML functions take only one argument. As a result, SML functions can have only one of

People have written games for the iPhone in Scheme. Because (some) Scheme-compilers compile down to C, it was easy to mix with Objective-C and integrate with XCode. I am aware of patches for Haskell and OCaml compilers to enable ARM/iOS-backends. But those appear unofficial and experimental/unstable. I prefer a static haskell/ML-type type-system over Scheme's dynamic typing. Is there a stable ML/SML/Haskell compiler which generates C-code so that it can be used in a similar way as Scheme/Gambit-C? I can't help with ML, but have you looked at JHC ? JHC is a whole-program optimizing Haskell

What are the limits of type inference? Which type systems have no general inference algorithm? Joe Wells showed that type inference is undecidable for System F, which is the most basic polymorphic lambda calculus, independently discovered by Girard and Reynolds. This is the most important result showing the limits of type inference. Here's an important problem that is still open: what is the best way to integrate Generalized Algebraic Data Types into Hindley-Milner type inference? Every year Simon Peyton Jones comes up with a new answers, which is supposedly better than the previous year's

Functional depth first search is lovely in directed acyclic graphs. In graphs with cycles however, how do we avoid infinite recursion? In a procedural language I would mark nodes as I hit them, but let's say I can't do that. A list of visited nodes is possible, but will be slow because using one will result in a linear search of that list before recurring. A better data structure than a list here would obviously help, but that's not the aim of the game, because I'm coding in ML - lists are king, and anything else I will have to write myself. Is there a clever way around this issue? Or will I