Reason 101:
variable assignment with let keyword cannot is immutable, but you can set it to mutable by assign to ref()
example JS:
let count = 0;
count ++;
in reason:
/* let count = 0; this is immutable */
let count = ref(count);
count := count ^ + 1;
for string concat:
let stringConcat = “some string” ++ variable ++ “another string“;
array in ReasonML is using [|”a”, “b”, “c”|] /* | = pipe symbol */
let test = [|
“a”,
“b”,
“c”
|];
and
list = [
“a”,
“b”,
“c”
];
list is immutable.
in list you can assign a new list like so,
let list = [
“d”,
…list
]; /* this is like a appending “d” to a create new list but this is not effective, so use list prime */
let list’ = [
“d”,
…list
]; /* notice the single quote beside the name, this is like slightly change of the list with new name list */
Array are really good at random access indexing and accessing
list is really good at appending and create a new list without change
function syntax is same as JS, however In reason everything is return automatically, let say:
let square = x => x * x;
/* this will return x * x * in reason;
Piping for function: piping is like take in the parameter and from left put in the right side…
“string” |> someFunction
this is like someFunction(“string”);
|> is old syntax which takes in the parameter and put it as last argument,
“string” |> someFunction(firstArgument);
and this is like someFunction(firstArgument, “string”);
where new syntax is which will take the parameter and put on left hand side, use |.
“string” |. someFunction(firstArgument);
which is like someFunction(“string”, firstArgument);
piping is really useful when you want to execute multiple level of functions:
example: someFunction(anotherFunction(moreFunction(“string”)))
this is so difficult to read, so do like this:
“string” |. moreFunction |. anotherFunction |. someFunction;
Statement shorthand:
if (x == y) ? true : false;
which is same in reason.
same time you can use if else in reason, however I realised you can’t use just if in reasonml, it has to go with else:
if (x == y) {
true;
} else {
false;
}
also in javascript if is statement which means you can’t assign to a variable with if statement, but in reason you can:
let checkIf =
if (x == y) {
true;
} else {
false;
}
Pattern match is much:
switch x {
| y => true
| _ => false
}
_ is like all other case …
type variants are like list of variants types, this or that like constructors,
type days =
| Monday
| Tuesday
| Wednesday
….
required to use cap for the naming.
can be good for type checking
example :
switch (day) {
| Monday => “monday”
| Tuesday => “tuesday”
| Wednesday => “wednesday”
}
