Merge pull request #10 from ritesh404/feat/update-caseof

feat: caseof can pattern match strings and numbers

src/adt/Either/either.test.ts

@@ -191,13 +191,15 @@ test("Either", t => {
 
     caseOf(
         {
-            Right: v => t.equal(v, 1, "successful Right pattern match")
+            Right: v => t.equal(v, 1, "successful Right pattern match"),
+            Left: x => x
         },
         a
     );
     caseOf(
         {
-            Left: v => t.equal(v, 1, "successful Left pattern match")
+            Left: v => t.equal(v, 1, "successful Left pattern match"),
+            Right: x => x
         },
         e
     );

src/adt/Either/index.ts

@@ -159,7 +159,8 @@ class Left<A, B> extends Either<A, B> {
         return `Left(${this.getValue()})`;
     }
 
-    public caseOf(o: { Left: Function }) {
+    public caseOf(o: { Left: Function; Right: Function }) {
+        if (!o.Right) throw new Error("Either: case for Right missing");
         if (o.Left) return o.Left(this.getValue());
         else throw Error("Either: Expected Left!");
     }
@@ -210,7 +211,8 @@ class Right<A, B> extends Either<A, B> {
         return `Right(${this.getValue()})`;
     }
 
-    public caseOf(o: { Right: Function }) {
+    public caseOf(o: { Right: Function; Left: Function }) {
+        if (!o.Left) throw new Error("Either: case for Left missing");
         if (o.Right) return o.Right(this.getValue());
         else throw Error("Either: Expected Right");
     }

src/adt/Maybe/index.ts

@@ -129,7 +129,8 @@ export class Nothing<A> extends Maybe<A> {
         return "Nothing()";
     }
 
-    public caseOf(o: { Nothing: Function }) {
+    public caseOf(o: { Nothing: Function; Just: Function }) {
+        if (!o.Just) throw new Error("Maybe: case for Just missing");
         if (o.Nothing) return o.Nothing();
         else throw Error("Maybe: Expected Nothing!");
     }
@@ -172,7 +173,8 @@ export class Just<A> extends Maybe<A> {
         return `Just(${this.getValue()})`;
     }
 
-    public caseOf(o: { Just: Function }) {
+    public caseOf(o: { Just: Function; Nothing: Function }) {
+        if (!o.Nothing) throw new Error("Maybe: case for Nothing missing");
         if (o.Just) return o.Just(this.getValue());
         else throw Error("Maybe: Expected Just");
     }

src/adt/Maybe/maybe.test.ts

@@ -160,13 +160,15 @@ test("Maybe", t => {
 
     caseOf(
         {
-            Just: v => t.equal(v, 1, "successful Just pattern match")
+            Just: v => t.equal(v, 1, "successful Just pattern match"),
+            Nothing: x => x
         },
         a
     );
     caseOf(
         {
-            Nothing: v => t.notOk(v, "successful Nothing pattern match")
+            Nothing: v => t.notOk(v, "successful Nothing pattern match"),
+            Just: x => x
         },
         e
     );

src/function/caseOf/caseof.test.ts

@@ -0,0 +1,36 @@
+import * as test from "tape";
+import caseOf from "./";
+
+import Either from "../../adt/Either";
+
+test("caseOf", t => {
+    const e1 = Either.of(1);
+    t.equals(
+        caseOf({ Right: v => v + 1, Left: x => x }, e1),
+        2,
+        "pattern match"
+    );
+    t.throws(
+        () => caseOf({ Right: v => v + 1, Left: x => x }, "hello"),
+        "pattern match fail"
+    );
+    t.equals(
+        caseOf({ string: x => x, _: x => x }, "string"),
+        "string",
+        "pattern match strings"
+    );
+    t.equals(
+        caseOf({ string: x => x, _: x => x }, 1),
+        1,
+        "pattern match numbers"
+    );
+    t.throws(
+        () => caseOf({ str: x => x }, "hello"),
+        "Must provide default case for strings"
+    );
+    t.throws(
+        () => caseOf({ 5: x => x }, 1),
+        "Must provide default case for numbers"
+    );
+    t.end();
+});

src/function/caseOf/index.ts

@@ -2,8 +2,19 @@ import PatternMatch from "../../interface/Patternmatch";
 import curry from "../curry";
 import isFunction from "../isFunction";
 
-function caseOf(o: { [k: string]: (a: any) => any }, p: PatternMatch): any {
-    if (isFunction(p.caseOf)) return p.caseOf(o);
-    else throw Error("Unable to pattern match");
+function caseOf(
+    o: { [k: string]: (a: any) => any },
+    p: PatternMatch | string | number
+): any {
+    if (typeof p === "string" || p instanceof String || typeof p === "number") {
+        if (!o._ && !o.default) throw Error("caseOf: Default case missing");
+        else {
+            // @ts-ignore
+            if (o[p]) return o[p](p);
+            if (o._) return o._(p);
+            if (o.default) return o.default(p);
+        }
+    } else if (isFunction(p.caseOf)) return p.caseOf(o);
+    else throw Error("caseOf: Unable to pattern match");
 }
 export default curry(caseOf);

src/function/helpers.test.ts

@@ -3,7 +3,6 @@ import bimap from "./bimap";
 import chain from "./chain";
 import constant from "./constant";
 import compose from "./compose";
-import caseOf from "./caseOf";
 import curry from "./curry";
 import Either from "../adt/Either";
 import fmap from "./fmap";
@@ -128,12 +127,6 @@ test("Helpers", t => {
         "compose return the same result as calling the functions individually"
     );
 
-    t.equals(caseOf({ Right: v => v + 1 }, e1), 2, "pattern match");
-    t.throws(
-        () => caseOf({ Right: v => v + 1 }, "hello"),
-        "pattern match fail"
-    );
-
     t.throws(() => liftAn(1, [e1]), "liftAn expects a function");
     t.throws(() => liftAn(add2, []), "liftAn expects a Array of Apply");
     t.equals(unwrap(liftAn(add2, [e1])), 3, "liftAn");