Standard ML of New Jersey (SML/NJ)
SML/NJ is a popular implementation of the Standard ML programming language that was co-developed jointly by Bell Laboratories and Princeton University. It is released under a BSD like license.
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Questions tagged [smlnj]
866 questions
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SML - Using map to return combined results
I have these functions:
fun IsDivisible(t, t2) = if t mod t2 > 0 then true else false;
fun IsDivisibleFilter(ts, t) = List.filter(fn x => IsDivisible(x, t)) ts;
fun IsDivisibleMap(ts, ts2) = map(fn x => IsDivisibleFilter(ts, x))…
Lance_P
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How does SML evaluate the arguments passed into currying function?
I write two different pieces of code trying to figure out the substitution v.s. evaluation order SML uses with respect to function arguments. But the results confused me a lot.
The toy function is as below
fun pow x y = if y=0 then 1 else x * (pow x…
Ze Gao
- 91
- 1
- 7
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1 answer
Why am I getting "unbound variable or constructor" in my SML program
I have written a method to return the first element in a list that satisfies a function (passed in via currying). The function returns NONE or SOME depending on whether or not the element satisfies a condition. I'm using Pattern Matching
However,…
Dave
- 8,095
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1 answer
Standard ML multiple condition statement
I am about finished with a script I am writing but I have one last condition statement to add to my function.
fun whileloop (x:real,a:int,b:real) =
if (a<1)
then (x,a,b)
else whileloop(x+1.0,a-1,b-1.0)
This is my current loop I have…
Busta
- 81
- 9
0
votes
1 answer
Returning two variables in SML
I have a function below that uses variable X and variable A.
How can I return both of these variables to be able to use these values further down the program.
val a = 1000;
val x = 5;
fun test (x,a) =
if (a<1) then(
x)
else(
…
Busta
- 81
- 9
0
votes
1 answer
Creating an array in smlnj
Ok, let me start off by saying I am a super newbie in Standard ML. I am literally just beginning to program in this language. To be honest with you, I don't plan on digging too deep in this language. I just need to accomplish a one-time task and…
Busta
- 81
- 9
0
votes
2 answers
how to split a list into two lists in which the first has the positive entries and the second has non-positive entries-SML
I am a new to SML and I want to write a function splitup : int list -> int list * int list that given a list of integers creates from two lists of integers, one containing the non-negative entries, the other containing the negative entries.
Here is…
DennngP
- 37
- 8
0
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1 answer
Convert "char list array" to "char array array" in SML
I am trying to convert the following variable:
- final "in1.txt";
val it = [|[#"S",#".",#".",#"."],[#".",#".",#".",#"."],[#"W",#".",#"X",#"W"],
[#".",#".",#"X",#"E"]|] : char list array
from 'char list array' to 'char array array' in SMLNJ. The…
Zehanort
- 458
- 2
- 10
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1 answer
2D map to graph in Sml
I have a 2D map as input from a file ,line by line and I want to save it and run a Bfs or Dijkstra to find the shortest path from Start (marked as S ) to end (marked as E),what's the proper structure to save the information? My implementation in c++…
orfeas
- 1
0
votes
1 answer
How to output a string list to a textfile in SML?
I am trying to write a method that when called, given a string list and the name of the output file, will output each element to the output file in SML. I have tried this, but it doesn't seem to work.
fun quit(outFile: string, list: string list) =
…
arizq29
- 11
- 5
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votes
1 answer
Defining types in SML?
If I want to check if a string starts with a letter and the rest of the characters can either be a letter or number, how would I define a datatype that is defined by those conditions? Or would pattern matching be the better route and if so, how…
arizq29
- 11
- 5
0
votes
1 answer
SML: Function composition with isSome
I have the following examples and they do not work even though the types do matchup with each other
- isSome;
val it = fn : 'a option -> bool
- SOME;
val it = fn : 'a -> 'a option
- val my_converter = (fn x => if x = 5 then SOME x else NONE);
val…
Har
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Adding items to list SML
I'm very new to SML and I'm trying to add some items to a list
fun foo(inFile : string, outFile : string) = let
val file = TextIO.openIn inFile
val outStream = TextIO.openOut outFile
val contents = TextIO.inputAll file
val lines = String.tokens (fn…
dws
- 3
- 2
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votes
1 answer
Call a Python file in a SML program?
I was wondering if it is possible to call a python file in an SML program, and if so how can you do it? I have tried researching how to do this, but have only found documentation on how to call other SML files.
arizq29
- 11
- 5
0
votes
2 answers
SML splitting string on first space
As of right now I am reading in an entire input file using inputAll and then using String.tokens to split each word at every occurrence of space.
val file = TextIO.openIn input
val _input = TextIO.inputAll file
val _ = TextIO.closeIn…
Truth
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