sml

I'm having some trouble using SML/NJ interactive system, namely, that when I try to use my arrow keys (either left or right to make a correction in the expression I've typed, up to repeat the last expression), my Terminal prints codes. (e.g. ^[[A for up ^[[D for left, etc.). While I can still use the system, it makes it very tedious. I've looked around in Control.Compiler, is there something I'm missing? For whatever its worth, I'm using the Mac Terminal. Thanks ^_^ Try this. You can use socat to add readline support to many things: socat READLINE EXEC:sml I just realized you're on OS X. socat

I have been trying to explain the difference between switch statements and pattern matching(F#) to a couple of people but I haven't really been able to explain it well..most of the time they just look at me and say "so why don't you just use if..then..else". How would you explain it to them? EDIT! Thanks everyone for the great answers, I really wish I could mark multiple right answers. Having formerly been one of "those people", I don't know that there's a succinct way to sum up why pattern-matching is such tasty goodness. It's experiential. Back when I had just glanced at pattern-matching and

I need to read file in ML (SLMNJ) and save it in some structures. I need to read some data that points to graph declaration: [( 1 , 2 , 13 ),( 2 , 3 , 3 ),( 2 , 4 , 8 ),( 2 , 5 , 4 ),( 3 , 1 , 5 ),( 3 , 4 , 1 ),( 4 , 6 , 5 ),( 5 , 5 , 5 ),( 6 , 4 , 6 )] (first number: name of the node , secend number: name of connected node , third number weight for this mane (each () show one mane ) ) for expamle this is test input how to read file and which structure to save it for reading from file follow this to list of string per line : val infile = "c:/input.txt" ; fun readlist (infile : string) = let

I don't know why my code doesn't work. fun lookup _ [] = 0 | lookup key ((k,v)::entries) = if k = key then v else (lookup key entries) That's what happened when I tested it in cmd. val lookup = fn : ''a -> (''a * int) list -> int - lookup (1,[(1,2),(2,3)]); val it = fn : ((int * (int * int) list) * int) list -> int There's nothing wrong with your code, you just didn't call lookup with enough arguments. You make a common mistakes among beginner SML programmers coming from other languages. I'll try to clarify that. First, the most important thing to know about functions in Standard ML is this:

I am new to SML (and programming, actually). fun readlist (infile : string) = let val ins = TextIO.openIn infile fun loop ins = case TextIO.inputLine ins of SOME line => line :: loop ins | NONE => [] in loop ins before TextIO.closeIn ins end ; This is a program I encountered here. How do I use SOME and NONE, and how to use 'before'? molbdnilo The option data type is used if there is a possibility of something having no valid value. For instance, fun divide x y = if y == 0 then NONE else SOME (x / y) could be used if you need to handle the special case of division by zero without resorting to