Add Multi-Argument Functions As Syntactic Sugar as a reasonml til

reason/multi-argument-functions-as-syntactic-sugar.md

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+# Multi-Argument Functions As Syntactic Sugar
+
+When writing a multi-argument function, like the following `adder` function:
+
+```reason
+let adder = (x, y) => x + y;
+
+adder(2, 3); /* => 5 */
+```
+
+We are utilizing a syntactic sugar of the function syntax. The same function
+can be written as such:
+
+```reason
+let adder = (x) => (y) => x + y;
+
+adder(2, 3); /* => 5 */
+```
+
+As you can see, we can apply the function in the same way.
+
+This is useful because it means we can partially apply (or _curry_) our
+functions to create other functions.
+
+```reason
+let adder = (x, y) => x + y;
+let twoAdder = adder(2);
+
+twoAdder(5); /* => 7 */
+```
+
+[source
+code](https://reasonml.github.io/en/try.html?reason=DYUwLgBAhgJjICcIF4IAoAeBKFA+dAnjsvhhANQQEDcAULQFIDOAdMAPYDmas8CaAFgA0EAKxYsdWqEhgA7uwCCcRCmgr+AJkn1mbLmnlKNacZKA)