Variant vs Polymorphic Variant

variants.re

/* Read about variants in https://reasonml.github.io/guide/language/variant */

/* Variant */

type thing = | Int(string) | Float;
type otherThing = | Int(int) | Float;

let a = Int(1);

/* Type Error: This expression has type string but an expression was expected of type int */
let b = Int("some string");

switch(a) {
 | Int(a) => Js.log(a)
 | Float => Js.log("it's a float!")
};

/* Polymorphic Variant */

let a = `Int(1);
let b = `Int("some string");

switch(a) {
 | `Int(a) => Js.log(a)
 | `Float => Js.log("it's a float!")
};

switch(b) {
 | `Int(b) => Js.log(b)
 | `Float => Js.log("it's a float!")
};