replace instanceof checks with valued _tags, fix #96 (#97)

CHANGELOG.md

@@ -12,6 +12,14 @@
 **Note**: Gaps between patch versions are faulty/broken releases.
 **Note**: A feature tagged as Experimental is in a high state of flux, you're at risk of it changing without notice.
 
+# 0.2.9
+
+- **New Feature**
+  - add Monoidal type class (@gcanti)
+- **Bug Fix**
+  - fix `foldMap`, closes #89 (@gcanti)
+  - replace `instanceof` checks with valued `_tag`s, fix #96 (@gcanti, @sledorze)
+
 # 0.2.8
 
 - **New Feature**

package.json

@@ -1,6 +1,6 @@
 {
   "name": "fp-ts",
-  "version": "0.2.8",
+  "version": "0.2.9",
   "description": "Functional programming in TypeScript",
   "files": [
     "lib",

src/Either.ts

@@ -35,7 +35,7 @@ export class Left<L, A> implements
   FantasyBifunctor<URI, L, A> {
 
   static of = of
-  readonly _tag: 'Left'
+  readonly _tag = 'Left'
   readonly _L: L
   readonly _A: A
   readonly _URI: URI
@@ -101,7 +101,7 @@ export class Right<L, A> implements
   FantasyBifunctor<URI, L, A> {
 
   static of = of
-  readonly _tag: 'Right'
+  readonly _tag = 'Right'
   readonly _L: L
   readonly _A: A
   readonly _URI: URI
@@ -222,11 +222,11 @@ export function chainRec<L, A, B>(f: (a: A) => Either<L, Either<A, B>>, a: A): E
 }
 
 export function isLeft<L, A>(fa: Either<L, A>): fa is Left<L, A> {
-  return fa instanceof Left
+  return fa._tag === 'Left'
 }
 
 export function isRight<L, A>(fa: Either<L, A>): fa is Right<L, A> {
-  return fa instanceof Right
+  return fa._tag === 'Right'
 }
 
 export function left<L, A>(l: L): Either<L, A> {

src/Option.ts

@@ -34,7 +34,7 @@ export class None<A> implements
   static empty = empty
   static zero = zero
   static value: Option<any> = new None()
-  readonly _tag: 'None'
+  readonly _tag = 'None'
   readonly _A: A
   readonly _URI: URI
   constructor() {
@@ -114,7 +114,7 @@ export class Some<A> implements
   static of = of
   static empty = empty
   static zero = zero
-  readonly _tag: 'Some'
+  readonly _tag = 'Some'
   readonly _A: A
   readonly _URI: URI
   constructor(public readonly value: A) {}
@@ -238,7 +238,7 @@ export function getStaticMonoid<A>(semigroup: StaticSemigroup<A>): StaticMonoid<
 }
 
 export function isSome<A>(fa: Option<A>): fa is Some<A> {
-  return fa instanceof Some
+  return fa._tag === 'Some'
 }
 
 export function isNone<A>(fa: Option<A>): fa is None<A> {

src/These.ts

@@ -25,7 +25,7 @@ export type These<L, A> = This<L, A> | That<L, A> | Both<L, A>
 
 export class This<L, A> {
   static of = of
-  readonly _tag: 'This'
+  readonly _tag = 'This'
   readonly _L: L
   readonly _A: A
   readonly _URI: URI
@@ -75,7 +75,7 @@ export class This<L, A> {
 
 export class That<L, A> {
   static of = of
-  readonly _tag: 'That'
+  readonly _tag = 'That'
   readonly _L: L
   readonly _A: A
   readonly _URI: URI
@@ -125,7 +125,7 @@ export class That<L, A> {
 
 export class Both<L, A> {
   static of = of
-  readonly _tag: 'This'
+  readonly _tag = 'Both'
   readonly _L: L
   readonly _A: A
   readonly _URI: URI
@@ -219,15 +219,15 @@ export function traverse<F extends HKTS>(applicative: StaticApplicative<F>): <L,
 }
 
 export function isThis<L, A>(fa: These<L, A>): fa is This<L, A> {
-  return fa instanceof This
+  return fa._tag === 'This'
 }
 
 export function isThat<L, A>(fa: These<L, A>): fa is That<L, A> {
-  return fa instanceof That
+  return fa._tag === 'That'
 }
 
 export function isBoth<L, A>(fa: These<L, A>): fa is Both<L, A> {
-  return fa instanceof Both
+  return fa._tag === 'Both'
 }
 
 export function this_<L, A>(l: L): These<L, A> {

src/Validation.ts

@@ -35,7 +35,7 @@ export class Failure<L, A> implements
   FantasyAlt<URI, A> {
 
   static of = of
-  readonly _tag: 'Failure'
+  readonly _tag = 'Failure'
   readonly _L: L
   readonly _A: A
   readonly _URI: URI
@@ -109,7 +109,7 @@ export class Success<L, A> implements
   FantasyAlt<URI, A> {
 
   static of = of
-  readonly _tag: 'Success'
+  readonly _tag = 'Success'
   readonly _L: L
   readonly _A: A
   readonly _URI: URI
@@ -220,11 +220,11 @@ export function traverse<F extends HKTS>(applicative: StaticApplicative<F>): <L,
 }
 
 export function isFailure<L, A>(fa: Validation<L, A>): fa is Failure<L, A> {
-  return fa instanceof Failure
+  return fa._tag === 'Failure'
 }
 
 export function isSuccess<L, A>(fa: Validation<L, A>): fa is Success<L, A> {
-  return fa instanceof Success
+  return fa._tag === 'Success'
 }
 
 export function failure<L, A>(semigroup: StaticSemigroup<L>, l: L): Validation<L, A> {