refactor: type + constructors refactor

6 files changed, 60 insertions, 62 deletions

diff --git a/TODO.md b/TODO.md
index 5760fde..51850a3 100644
--- a/TODO.md
+++ b/TODO.md
@@ -6,16 +6,12 @@
   - [ ] Parse: `{2, 5}` quantifiers
   - [ ] Eval: `^$` start-end
   - [ ] Func: filter
-  - [ ] Func: match
+  - [ ] Func: matchAll
   - [ ] Func: replace
   - [ ] Not/Inverse
   - [ ] Named capture groups
   - [ ] Non-capture groups
 
-## Issues
-  - [ ] . should not match for empty list
-
 ## Refactor
-  - [ ] Remove default null for constructors
   - [ ] Create group inside PropertyMatch and send single `expr`
 
diff --git a/src/parser/index.ts b/src/parser/index.ts
index 386fa94..c61364d 100644
--- a/src/parser/index.ts
+++ b/src/parser/index.ts
@@ -20,15 +20,15 @@ import {
 } from './utils'
 import { Expr, ListExpr } from '../types'
 
-const start = mapTo(symbol('^'), _ => Expr.Start(null))
-const end = mapTo(symbol('$'), _ => Expr.End(null))
-const anyItem = mapTo(symbol('.'), _ => Expr.AnyItem(null))
-const nextItem = mapTo(symbol(','), _ => Expr.NextItem(null))
-const anyString = mapTo(symbol('\\s'), _ => Expr.AnyString(null))
-const anyNumber = mapTo(symbol('\\n'), _ => Expr.AnyNumber(null))
-const anyBool = mapTo(symbol('\\b'), _ => Expr.AnyBool(null))
-const truthy = mapTo(symbol('\\T'), _ => Expr.Truthy(null))
-const falsey = mapTo(symbol('\\F'), _ => Expr.Falsey(null))
+const start = mapTo(symbol('^'), _ => Expr.Start())
+const end = mapTo(symbol('$'), _ => Expr.End())
+const anyItem = mapTo(symbol('.'), _ => Expr.AnyItem())
+const nextItem = mapTo(symbol(','), _ => Expr.NextItem())
+const anyString = mapTo(symbol('\\s'), _ => Expr.AnyString())
+const anyNumber = mapTo(symbol('\\n'), _ => Expr.AnyNumber())
+const anyBool = mapTo(symbol('\\b'), _ => Expr.AnyBool())
+const truthy = mapTo(symbol('\\T'), _ => Expr.Truthy())
+const falsey = mapTo(symbol('\\F'), _ => Expr.Falsey())
 
 const wrapQuantifiers: (e: ParserResult<Expr>) => ParserResult<Expr> = chain(
   ([expr, input]) =>
diff --git a/src/types.ts b/src/types.ts
index 07e6e8a..d30413d 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -1,27 +1,27 @@
 import {Option} from "fp-ts/lib/Option"
 import { constructors, Union } from "./utils"
 
-type ExprT = {
-  Start: null,
-  End: null,
+type _ = never
+
+export type Expr = Union<{
+  Start: _,
+  End: _,
   Optional: { expr: Expr },
   OneOrMore: { expr: Expr },
   ZeroOrMore: { expr: Expr },
-  NextItem: null,
-  AnyItem: null,
+  NextItem: _,
+  AnyItem: _,
   Or: { left: Expr, right: Expr[] },
-  AnyString: null,
-  AnyNumber: null,
-  AnyBool: null,
-  Truthy: null,
-  Falsey: null,
+  AnyString: _,
+  AnyNumber: _,
+  AnyBool: _,
+  Truthy: _,
+  Falsey: _,
   Group: { exprs: Expr[] },
   PropertyMatch: { name: string, exprs: Expr[] },
-}
-
-export type Expr = Union<ExprT>
+}>
 
-export const Expr = constructors<ExprT>()
+export const Expr = constructors<Expr>()
 
 export type ListExpr = [
   Option<Expr>,
diff --git a/src/utils.ts b/src/utils.ts
index 15d5fb0..66c4c53 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -3,19 +3,22 @@ export const eq =
   (b: T): boolean =>
     a === b
 
-type TagValue<T, N> = T extends Tag<N, infer V> ? V : never;
+type TagValue<T, N> = T extends Tag<N, infer V> ? V : never
 
 export const match =
-  <R, T extends Tag<string, any>>
-  (pattern: { [key in T['tag'] | '_']?: (v: TagValue<T, key>) => R }) =>
-    (tag: T): R =>
-      (pattern[tag.tag] || pattern._ as any)(tag.value)
+  <R, T extends Tag<string, any>>(pattern: {
+    [key in T['tag'] | '_']?: (v: TagValue<T, key>) => R
+  }) =>
+  (tag: T): R =>
+    (pattern[tag.tag] || (pattern._ as any))(tag.value)
 
 type Tag<N, V> = { tag: N; value: V }
 export type Union<T> = { [N in keyof T]: Tag<N, T[N]> }[keyof T]
 
-export const constructors = <T extends Record<string, any>>(): {
-  [N in keyof T]: (value: T[N]) => Union<T> // Tag<N, T[N]>
+export const constructors = <T extends Tag<string, any>>(): {
+  [N in T['tag']]: TagValue<T, N> extends null|never
+    ? (value?: null | never) => T
+    : (value: TagValue<T, N>) => T
 } =>
   new Proxy(
     {},
@@ -27,4 +30,3 @@ export const constructors = <T extends Record<string, any>>(): {
   ) as any
 
 export const jlog = (x: any) => console.log(JSON.stringify(x, null, 2))
-
diff --git a/tests/eval.spec.ts b/tests/eval.spec.ts
index ca06033..2d7e1c0 100644
--- a/tests/eval.spec.ts
+++ b/tests/eval.spec.ts
@@ -13,7 +13,7 @@ describe('Eval', () => {
       [
         Expr.OneOrMore({
           expr: Expr.Group({
-            exprs: [Expr.AnyNumber(null), Expr.Truthy(null)],
+            exprs: [Expr.AnyNumber(), Expr.Truthy()],
           }),
         }),
       ],
@@ -28,14 +28,14 @@ describe('Eval', () => {
 
     const liexp: ListExpr = [
       none,
-      [Expr.AnyNumber(null), Expr.Truthy(null)],
+      [Expr.AnyNumber(), Expr.Truthy()],
       none,
     ]
     expect(find(liexp, list)).toEqual([1, 3, 5])
 
     const liexp2: ListExpr = [
       none,
-      [Expr.Falsey(null), Expr.Truthy(null)],
+      [Expr.Falsey(), Expr.Truthy()],
       none,
     ]
     expect(find(liexp2, list)).toEqual([])
@@ -47,8 +47,8 @@ describe('Eval', () => {
     const liexp: ListExpr = [
       none,
       [
-        Expr.AnyItem(null),
-        Expr.Group({ exprs: [Expr.AnyNumber(null), Expr.Truthy(null)] }),
+        Expr.AnyItem(),
+        Expr.Group({ exprs: [Expr.AnyNumber(), Expr.Truthy()] }),
       ],
       none,
     ]
@@ -69,9 +69,9 @@ describe('Eval', () => {
       [
         Expr.PropertyMatch({
           name: 'name',
-          exprs: [Expr.AnyString(null), Expr.Truthy(null)],
+          exprs: [Expr.AnyString(), Expr.Truthy()],
         }),
-        Expr.PropertyMatch({ name: 'age', exprs: [Expr.AnyNumber(null)] }),
+        Expr.PropertyMatch({ name: 'age', exprs: [Expr.AnyNumber()] }),
       ],
       none,
     ]
@@ -84,7 +84,7 @@ describe('Eval', () => {
 
     const liexp: ListExpr = [
       none,
-      [Expr.OneOrMore({ expr: Expr.AnyNumber(null) })],
+      [Expr.OneOrMore({ expr: Expr.AnyNumber() })],
       none,
     ]
     expect(find(liexp, list)).toEqual([1, 3, 5])
diff --git a/tests/parser.spec.ts b/tests/parser.spec.ts
index 4db0894..9bc891e 100644
--- a/tests/parser.spec.ts
+++ b/tests/parser.spec.ts
@@ -33,15 +33,15 @@ describe('Foobar', () => {
     expect(parser(/^ .\s(\n)\b  \T $/.source)).toEqual(
       right([
         [
-          some(Expr.Start(null)),
+          some(Expr.Start()),
           [
-            Expr.AnyItem(null),
-            Expr.AnyString(null),
-            Expr.Group({ exprs: [Expr.AnyNumber(null)] }),
-            Expr.AnyBool(null),
-            Expr.Truthy(null),
+            Expr.AnyItem(),
+            Expr.AnyString(),
+            Expr.Group({ exprs: [Expr.AnyNumber()] }),
+            Expr.AnyBool(),
+            Expr.Truthy(),
           ],
-          some(Expr.End(null)),
+          some(Expr.End()),
         ],
         '',
       ]),
@@ -50,13 +50,13 @@ describe('Foobar', () => {
     expect(parser(/^ \s* \T? \n+ $/.source)).toEqual(
       right([
         [
-          some(Expr.Start(null)),
+          some(Expr.Start()),
           [
-            Expr.ZeroOrMore({ expr: Expr.AnyString(null) }),
-            Expr.Optional({ expr: Expr.Truthy(null) }),
-            Expr.OneOrMore({ expr: Expr.AnyNumber(null) }),
+            Expr.ZeroOrMore({ expr: Expr.AnyString() }),
+            Expr.Optional({ expr: Expr.Truthy() }),
+            Expr.OneOrMore({ expr: Expr.AnyNumber() }),
           ],
-          some(Expr.End(null)),
+          some(Expr.End()),
         ],
         '',
       ]),
@@ -68,12 +68,12 @@ describe('Foobar', () => {
           none,
           [
             Expr.Or({
-              left: Expr.AnyString(null),
+              left: Expr.AnyString(),
               right: [
-                Expr.AnyBool(null),
+                Expr.AnyBool(),
                 Expr.Or({
-                  left: Expr.Truthy(null),
-                  right: [Expr.AnyNumber(null)],
+                  left: Expr.Truthy(),
+                  right: [Expr.AnyNumber()],
                 }),
               ],
             }),
@@ -93,9 +93,9 @@ describe('Foobar', () => {
           [
             Expr.PropertyMatch({
               name: 'name',
-              exprs: [Expr.AnyString(null), Expr.Truthy(null)],
+              exprs: [Expr.AnyString(), Expr.Truthy()],
             }),
-            Expr.PropertyMatch({ name: 'age', exprs: [Expr.AnyNumber(null)] }),
+            Expr.PropertyMatch({ name: 'age', exprs: [Expr.AnyNumber()] }),
           ],
           none,
         ],