refactor: change onType to match and take only one pattern and result (#22)

Pursuant to #12. Besides changing the name of onType to match, and only allowing one pattern and result in `match()`,
this PR also arranges that in place of an onType with lots of alternating PATTERN, VALUE, PATTERN, VALUE arguments, one now exports an _array_ of `match(PATTERN, VALUE)` items.

Doesn't quite fully resolve #12, because there is still the question of whether `match(...)` can be left out for a behavior that literally matches anything (current behavior), or whether `match(Passthru, behavior)` should be required for such cases.

Reviewed-on: #22
Co-authored-by: Glen Whitney <glen@studioinfinity.org>
Co-committed-by: Glen Whitney <glen@studioinfinity.org>

src/boolean/type.js

@@ -1,14 +1,14 @@
 import {BooleanT} from './BooleanT.js'
-import {onType} from '#core/helpers.js'
+import {match} from '#core/helpers.js'
 import {Returns, Type, TypeOfTypes, Undefined} from '#core/Type.js'
 import {NumberT} from '#number/NumberT.js'
 
 const bool = f => Returns(BooleanT, f)
 
-export const boolean = onType(
+export const boolean = [
-   BooleanT, bool(p => p),
+   match(BooleanT, bool(p => p)),
-   NumberT, bool(a => !!a),
+   match(NumberT, bool(a => !!a)),
-   TypeOfTypes, bool(() => true),
+   match(TypeOfTypes, bool(() => true)),
-   Undefined, bool(() => false),
+   match(Undefined, bool(() => false)),
-   [], bool(() => false)
+   match([], bool(() => false))
-)
+]

src/complex/Complex.js

@@ -1,5 +1,5 @@
 import {Type} from '#core/Type.js'
-import {onType} from '#core/helpers.js'
+import {match} from '#core/helpers.js'
 
 const isComplex = z => z && typeof z === 'object' && 're' in z && 'im' in z
 
@@ -10,15 +10,17 @@ function complexSpecialize(ComponentType) {
    const specTest = z => isComplex(z) && compTest(z.re) && compTest(z.im)
    const typeName = `Complex(${ComponentType})`
    if (ComponentType.concrete) {
-      const fromSpec = [
+      const fromSpec = [match(
-         ComponentType, math => r => ({re: r, im: ComponentType.zero})]
+         ComponentType, math => r => ({re: r, im: ComponentType.zero}))]
-      for (const  [matchType, fctry] of ComponentType.from.patterns) {
+      for (const {pattern, does} of ComponentType.from) {
-         fromSpec.push(this.specialize(matchType.type), math => {
+         fromSpec.push(match(
-            const compConv = fctry(math)
+            this.specialize(pattern.type),
-            return z => ({re: compConv(z.re), im: compConv(z.im)})
+            math => {
-         })
+               const compConv = does(math)
+               return z => ({re: compConv(z.re), im: compConv(z.im)})
+            }))
       }
-      const typeOptions = {from: onType(...fromSpec), typeName}
+      const typeOptions = {from: fromSpec, typeName}
       if ('zero' in ComponentType) {
          typeOptions.zero = {re: ComponentType.zero, im: ComponentType.zero}
          if ('one' in ComponentType) {

src/complex/__test__/Complex.spec.js

@@ -21,11 +21,11 @@ describe('Complex Type', () => {
       const convertImps = CplxNum.from
       let cnvNtoCN
       let cnvCBtoCN
-      for (const [pattern, convFactory] of convertImps.patterns) {
+      for (const {pattern, does} of convertImps) {
          if (pattern.match([NumberT])[0] === 1) {
-            cnvNtoCN = convFactory(math)
+            cnvNtoCN = does(math)
          } else if (pattern.match([Complex(BooleanT)])[0] === 1) {
-            cnvCBtoCN = convFactory(math)
+            cnvCBtoCN = does(math)
          }
       }
       assert.deepStrictEqual(cnvNtoCN(3.5), {re: 3.5, im: 0})

src/complex/type.js

@@ -1,10 +1,10 @@
 import {Complex} from './Complex.js'
-import {onType} from "#core/helpers.js"
+import {match} from "#core/helpers.js"
 import {Returns} from "#core/Type.js"
 import {Any} from "#core/TypePatterns.js"
 
-export const complex = onType(
+export const complex = [
-   Any, (math, T) => {
+   match(Any, (math, T) => {
       const z = math.zero(T)
       if (math.hasnan(T)) {
          const isnan = math.isnan.resolve([T])
@@ -15,8 +15,8 @@ export const complex = onType(
          })
       }
       return Returns(Complex(T), r => ({re: r, im: z}))
-   },
+   }),
-   [Any, Any], (math, [T, U]) => {
+   match([Any, Any], (math, [T, U]) => {
       if (T !== U) {
          throw new RangeError(
             'mixed complex types disallowed '
@@ -24,5 +24,4 @@ export const complex = onType(
       }
       return Returns(Complex(T), (r, m) => ({re: r, im: m}))
    })
-
+]
-

src/core/Type.js

@@ -21,7 +21,10 @@ export class Type extends Function {
       })
 
       this.test = f
-      this.from = options.from ?? {patterns: []} // mock empty Implementations
+      // we want property `from` to end up as an array of Matchers:
+      this.from = options.from
+         ? Array.isArray(options.from) ? options.from : [options.from]
+         : []
       if ('zero' in options) this.zero = options.zero
       if ('one' in options) this.one = options.one
       if ('nan' in options) this.nan = options.nan

src/core/TypeDispatcher.js

@@ -1,8 +1,8 @@
 import ArrayKeyedMap from 'array-keyed-map'
 
 import {
-   Implementations, ImplementationsGenerator, ResolutionError,
+   Implementations, ImplementationsGenerator, Matcher, ResolutionError,
-   isPlainFunction, isPlainObject, onType, types
+   isPlainFunction, isPlainObject, match, types
 } from './helpers.js'
 import {bootstrapTypes, Returns, whichType, Type} from './Type.js'
 import {matched, needsCollection, Passthru} from './TypePatterns.js'
@@ -45,11 +45,14 @@ export class TypeDispatcher {
    //    an Implementations that associates it with the Passthru pattern
    // -- a factory for entities, to be invoked to get the value of a key
    //    for any types. You can just merge that.
+   // -- a value or behavior that applies just when the types of an
+   //    argument match a type pattern. For that, you merge the result
+   //    of `match(PATTERN, VALUE)`
    // -- a collection of different values, or different behaviors, or
-   //    different factories for different types for a given key. For that
+   //    different factories for different lists of argument types for a
-   //    you merge an Implementations object that associates each item with
+   //    given key. For that you merge an array of results of `match`,
-   //    a TypePattern. An Implementation object can most easily be
+   //    so something like
-   //    generated with `onType(PATTERN, VALUE, PATTERN, VALUE,...)`
+   //    `[match(PATTERN, VALUE), match(PATTERN, VALUE), ...]`
    // Initially I thought those were all the possibilities. But then I
    // wanted to export something that when merged, would set the Passthru
    // pattern to a fresh specific object for that merge, but so that the
@@ -57,10 +60,10 @@ export class TypeDispatcher {
    // particular TypeDispatcher (this situation applies to the config object).
    // To produce that behavior, you need a fourth thing
    // -- an ImplementationGenerator, which is basically a function that
-   //    returns an Implementations object as above. As this is only needed
+   //    returns one of the last couple of options above. As this variant is
-   //    for a single entity that will be merged into multiple different
+   //    only needed for a single entity that will be merged into multiple
-   //    TypeDispatchers, there's not a big focus on making this convenient;
+   //    different TypeDispatchers, there's not a big focus on making
-   //    it's not expected to come up much.
+   //    specifying it convenient; it's not expected to come up much.
 
    merge(spec) {
       if (!spec) return
@@ -74,9 +77,7 @@ export class TypeDispatcher {
          // For special cases like types, config, etc, we can wrap
          // a function in ImplementationsGenerator to produce the thing
          // we should really merge:
-         if (val instanceof ImplementationsGenerator) {
+         if (val instanceof ImplementationsGenerator) val = val.generate()
-            val = val.generate()
-         }
 
          // Now dispatch on what sort of thing we are supposed to merge:
          if (val instanceof Type) {
@@ -100,7 +101,14 @@ export class TypeDispatcher {
 
          // Everything else we coerce into Implementations and deal with
          // right here:
-         if (!(val instanceof Implementations)) val = onType(Passthru, val)
+         if (val instanceof Matcher) val = new Implementations(val)
+         if (Array.isArray(val)) val = new Implementations(val)
+         if (!(val instanceof Implementations)) {
+            val = new Implementations(match(Passthru, val))
+         }
+
+         // hereafter we may assume that val is an instance of Implementations
+
          if (!(key in this)) {
             // Need to "bootstrap" the item:
             // We initially define it with a temporary getter, only
@@ -189,11 +197,11 @@ export class TypeDispatcher {
             this._behaviors[key] = new ArrayKeyedMap()
          }
 
-         // Now add all of the patterns of this implementation:
+         // Now add all of the matchers of this Implementations:
-         for (const [pattern, result] of val.patterns) {
+         for (const {pattern, does} of val.matchers) {
             if (pattern === Passthru) {
                if (key in this._fallbacks) this._disengageFallback(key)
-               this._fallbacks[key] = result
+               this._fallbacks[key] = does
             } else {
                this._clearBehaviorsMatching(key, pattern)
                // if it happens the same pattern is already in the
@@ -201,7 +209,7 @@ export class TypeDispatcher {
                const imps = this._implementations[key]
                const have = imps.findIndex(elt => pattern.equal(elt[0]))
                if (have >= 0) imps.splice(have, 1)
-               this._implementations[key].unshift([pattern, result])
+               this._implementations[key].unshift([pattern, does])
             }
          }
       }

src/core/TypePatterns.js

@@ -21,7 +21,7 @@ class MatchTypePattern extends TypePattern {
       if (position < typeSequence.length) {
          if (this.type.specializesTo(actual)) return [position + 1, actual]
          if (options.convert) {
-            for (const [pattern, convertor] of this.type.from.patterns) {
+            for (const {pattern, does: convertor} of this.type.from) {
                const [pos] = pattern.match([actual])
                if (pos === 1) {
                   return [position + 1, {actual, convertor, matched: this.type}]

src/core/__test__/TypeDispatcher.spec.js

@@ -4,7 +4,7 @@ import * as booleans from '#boolean/all.js'
 import * as generics from '#generic/all.js'
 import * as numbers from '#number/all.js'
 import {NumberT} from '#number/NumberT.js'
-import {onType, ResolutionError} from "#core/helpers.js"
+import {match, ResolutionError} from "#core/helpers.js"
 import {Any} from "#core/TypePatterns.js"
 import {Returns, NotAType} from "#core/Type.js"
 import {plain} from "#number/helpers.js"
@@ -20,10 +20,10 @@ describe('TypeDispatcher', () => {
       assert.strictEqual(incremental.add(-1.5, 0.5), -1)
       assert.throws(() => incremental.add(7, undefined), ResolutionError)
       // Make Undefined act like zero:
-      incremental.merge({add: onType(
+      incremental.merge({add: [
-         [Undefined, Any], (_m, [_U, T]) => Returns(T, (_a, b) => b),
+         match([Undefined, Any], (_m, [_U, T]) => Returns(T, (_a, b) => b)),
-         [Any, Undefined], (_m, [T]) => Returns(T, a => a)
+         match([Any, Undefined], (_m, [T]) => Returns(T, a => a))
-      )})
+      ]})
       assert.strictEqual(incremental.add(7, undefined), 7)
       assert.strictEqual(
          incremental.resolve('add', [TypeOfTypes, Undefined]).returns,
@@ -34,10 +34,10 @@ describe('TypeDispatcher', () => {
          NumberT)
       // Oops, changed my mind ;-), make it work like NaN with numbers:
       const alwaysNaN = Returns(NumberT, () => NaN)
-      incremental.merge({add: onType(
+      incremental.merge({add: [
-         [Undefined, NumberT], alwaysNaN,
+         match([Undefined, NumberT], alwaysNaN),
-         [NumberT, Undefined], alwaysNaN
+         match([NumberT, Undefined], alwaysNaN)
-      )})
+      ]})
       assert(isNaN(incremental.add(undefined, -3.25)))
       assert.strictEqual(
          incremental.add.resolve([Undefined, NumberT]).returns,
@@ -61,7 +61,7 @@ describe('TypeDispatcher', () => {
       assert.strictEqual(bgn.negate(true), -1)
       assert(bgn._behaviors.negate.has([BooleanT]))
       const deps = bgn._dependencies.negate
-      bgn.merge({number: onType([BooleanT], Returns(NumberT, b => b ? 2 : 0))})
+      bgn.merge({number: match([BooleanT], Returns(NumberT, b => b ? 2 : 0))})
       assert(!bgn._behaviors.negate.has([BooleanT]))
       assert.strictEqual(bgn.negate(true), -2)
    })

src/core/__test__/helpers.spec.js

@@ -1,16 +1,15 @@
 import assert from 'assert'
 import {
-   Implementations, onType, isPlainObject, isPlainFunction
+   Matcher, match, isPlainObject, isPlainFunction, Implementations
 } from '../helpers.js'
 import {Type, Undefined, TypeOfTypes} from '../Type.js'
 import {TypePattern} from '../TypePatterns.js'
 
 describe('Core helpers', () => {
-   it('defines what Implementations are', () => {
+   it('defines what Matchers are', () => {
-      const imps = onType(Undefined, 7, [TypeOfTypes, Undefined], -3)
+      const matcher = match([TypeOfTypes, Undefined], -3)
-      assert(imps instanceof Implementations)
+      assert(matcher instanceof Matcher)
-      assert(imps.patterns instanceof Array)
+      assert(matcher.pattern instanceof TypePattern)
-      assert(imps.patterns.every(([k]) => k instanceof TypePattern))
    })
 
    it('detects plain objects', () => {

src/core/helpers.js

@@ -1,21 +1,21 @@
 import {pattern, Passthru} from './TypePatterns.js'
 
-export class Implementations {
+export class Matcher {
-   constructor(imps) {
+   constructor(spec, facOrBehave) {
-      this.patterns = []
+      this.pattern = pattern(spec)
-      this._add(imps)
+      this.does = facOrBehave
-   }
-   _add(imps) {
-      for (let i = 0; i < imps.length; ++i) {
-         this.patterns.push([pattern(imps[i]), imps[++i]])
-      }
-   }
-   also(...imps) {
-      this._add(imps)
    }
 }
 
-export const onType = (...imps) => new Implementations(imps)
+export class Implementations {
+   constructor(impOrImps) {
+      if (Array.isArray(impOrImps)) {
+         this.matchers = impOrImps
+      } else this.matchers = [impOrImps]
+   }
+}
+
+export const match = (spec, facOrBehave) => new Matcher(spec, facOrBehave)
 
 export class ImplementationsGenerator {
    constructor(f) {
@@ -34,7 +34,7 @@ export class ImplementationsGenerator {
 // collection of types (and modifying the types in one would affect them
 // all). Hence we do:
 
-export const types = new ImplementationsGenerator(() => onType(Passthru, {}))
+export const types = new ImplementationsGenerator(() => match(Passthru, {}))
 
 export class ResolutionError extends TypeError {
    constructor(...args) {

src/coretypes/relational.js

@@ -1,8 +1,8 @@
-import {onType} from '#core/helpers.js'
+import {match} from '#core/helpers.js'
 import {TypeOfTypes, Undefined} from '#core/Type.js'
 import {boolnum} from '#number/helpers.js'
 
-export const indistinguishable = onType(
+export const indistinguishable = [
-   [Undefined, Undefined], boolnum(() => true),
+   match([Undefined, Undefined], boolnum(() => true)),
-   [TypeOfTypes, TypeOfTypes], boolnum((t, u) => t === u)
+   match([TypeOfTypes, TypeOfTypes], boolnum((t, u) => t === u))
-)
+]

src/coretypes/utils.js

@@ -1,47 +1,47 @@
-import {onType} from '#core/helpers.js'
+import {match} from '#core/helpers.js'
 import {NotAType, Returns, TypeOfTypes} from '#core/Type.js'
 import {Any} from "#core/TypePatterns.js"
 import {boolnum} from "#number/helpers.js"
 
-export const zero = onType(
+export const zero = [
-   Any, (math, T) => {
+   match(Any, (math, T) => {
       const z = math.zero(T)
       return Returns(T, () => z)
-   },
+   }),
-   TypeOfTypes, Returns(NotAType, t => {
+   match(TypeOfTypes, Returns(NotAType, t => {
       if ('zero' in t) return t.zero
       throw new RangeError(`type '${t}' has no zero element`)
-   })
+   }))
-)
+]
 
-export const one = onType(
+export const one = [
-   Any, (math, T) => {
+   match(Any, (math, T) => {
       const unit = math.one(T)
       return Returns(T, () => unit)
-   },
+   }),
-   TypeOfTypes, Returns(NotAType, t => {
+   match(TypeOfTypes, Returns(NotAType, t => {
       if ('one' in t) return t.one
       throw new RangeError(
          `type '${t}' has no unit element designated as "one"`)
-   })
+   }))
-)
+]
 
-export const hasnan = onType(
+export const hasnan = [
-   Any, (math, T) => {
+   match(Any, (math, T) => {
       const answer = math.hasnan(T)
       return Returns(math.typeOf(answer), () => answer)
-   },
+   }),
-   TypeOfTypes, boolnum(t => 'nan' in t)
+   match(TypeOfTypes, boolnum(t => 'nan' in t))
-)
+]
 
-export const nan = onType(
+export const nan = [
-   Any, (math, T) => {
+   match(Any, (math, T) => {
       const notanum = math.nan(T)
       return Returns(T, () => notanum)
-   },
+   }),
-   TypeOfTypes, Returns(NotAType, t => {
+   match(TypeOfTypes, Returns(NotAType, t => {
       if ('nan' in t) return t.nan
       throw new RangeError(
          `type '${t}' has no "not a number" element`)
-   })
+   }))
-)
+]

src/generic/arithmetic.js

@@ -1,8 +1,8 @@
-import {onType} from '#core/helpers.js'
+import {match} from '#core/helpers.js'
 import {Returns} from '#core/Type.js'
 import {Any} from '#core/TypePatterns.js'
 
-export const square = onType(Any, (math, T) => {
+export const square = match(Any, (math, T) => {
    const mult = math.multiply.resolve([T, T])
    return Returns(mult.returns, a => mult(a, a))
 })

src/generic/config.js

@@ -1,5 +1,5 @@
-import {ImplementationsGenerator, onType} from '#core/helpers.js'
+import {ImplementationsGenerator, match} from '#core/helpers.js'
 import {Passthru} from '#core/TypePatterns.js'
 
 export const config = new ImplementationsGenerator(
-    () => onType(Passthru, {relTol: 1e-12, absTol: 1e-15}))
+    () => match(Passthru, {relTol: 1e-12, absTol: 1e-15}))

src/generic/relational.js

@@ -1,10 +1,10 @@
 import {ReturnsAs} from './helpers.js'
-import {onType} from '#core/helpers.js'
+import {match} from '#core/helpers.js'
 import {Returns} from '#core/Type.js'
 import {Any, matched} from '#core/TypePatterns.js'
 import {boolnum} from '#number/helpers.js'
 
-export const equal = onType([Any, Any], (math, [T, U]) => {
+export const equal = match([Any, Any], (math, [T, U]) => {
    // Finding the correct signature of `indistinguishable` to use for
    // testing (approximate) equality is tricky, because T or U might
    // need to be converted for the sake of comparison, and some types
@@ -38,7 +38,7 @@ export const equal = onType([Any, Any], (math, [T, U]) => {
 // now that we have `equal` and `exceeds`, pretty much everything else should
 // be easy:
 
-export const compare = onType([Any, Any], (math, [T, U]) => {
+export const compare = match([Any, Any], (math, [T, U]) => {
    const eq = math.equal.resolve([T, U])
    const gt = math.exceeds.resolve([T, U])
    const zero = math.zero(T) // asymmetry here is unfortunate, but we have
@@ -70,7 +70,7 @@ export const compare = onType([Any, Any], (math, [T, U]) => {
    })
 })
 
-export const sign = onType(Any, (math, T) => {
+export const sign = match(Any, (math, T) => {
    const zero = math.zero(T)
    const comp = math.compare.resolve([T, T])
    return ReturnsAs(comp, t => comp(t, zero))
@@ -81,25 +81,25 @@ export const unequal = (math, types) => {
    return ReturnsAs(eq, (...args) => !eq(...args))
 }
 
-export const larger = onType([Any, Any], (math, [T, U]) => {
+export const larger = match([Any, Any], (math, [T, U]) => {
    const eq = math.equal.resolve([T, U])
    const bigger = math.exceeds.resolve([T, U])
    return boolnum((t, u) => !eq(t, u) && bigger(t, u))(math)
 })
 
-export const largerEq = onType([Any, Any], (math, [T, U]) => {
+export const largerEq = match([Any, Any], (math, [T, U]) => {
    const eq = math.equal.resolve([T, U])
    const bigger = math.exceeds.resolve([T, U])
    return ReturnsAs(bigger, (t, u) => eq(t, u) || bigger(t, u))
 })
 
-export const smaller = onType([Any, Any], (math, [T, U]) => {
+export const smaller = match([Any, Any], (math, [T, U]) => {
    const eq = math.equal.resolve([T, U])
    const bigger = math.exceeds.resolve([U, T])
    return boolnum((t, u) => !eq(t, u) && bigger(u, t))(math)
 })
 
-export const smallerEq = onType([Any, Any], (math, [T, U]) => {
+export const smallerEq = match([Any, Any], (math, [T, U]) => {
    const eq = math.equal.resolve([T, U])
    const bigger = math.exceeds.resolve([U, T])
    return ReturnsAs(bigger, (t, u) => eq(t, u) || bigger(u, t))

src/generic/utils.js

@@ -1,5 +1,5 @@
 import {ReturnsAs} from './helpers.js'
-import {onType, ResolutionError} from '#core/helpers.js'
+import {ResolutionError} from '#core/helpers.js'
 import {Returns} from '#core/Type.js'
 import {Any} from "#core/TypePatterns.js"
 

src/number/NumberT.js

@@ -1,9 +1,9 @@
 import {Type} from '#core/Type.js'
-import {onType} from '#core/helpers.js'
+import {match} from '#core/helpers.js'
 import {BooleanT} from '#boolean/BooleanT.js'
 
 export const NumberT = new Type(n => typeof n === 'number', {
-    from: onType(BooleanT, math => math.number.resolve([BooleanT])),
+    from: match(BooleanT, math => math.number.resolve([BooleanT])),
     one: 1,
     zero: 0,
     nan: NaN

src/number/__test__/NumberT.spec.js

@@ -14,9 +14,9 @@ describe('NumberT Type', () => {
    it('can convert from BooleanT to NumberT', () => {
       const convertImps = NumberT.from
       let cnvBtoN
-      for (const [pattern, convFactory] of convertImps.patterns) {
+      for (const {pattern, does} of convertImps) {
          if (pattern.match([BooleanT])[0] === 1) {
-            cnvBtoN = convFactory(math)
+            cnvBtoN = does(math)
             break
          }
       }

src/number/helpers.js

@@ -1,9 +1,9 @@
 import {NumberT} from './NumberT.js'
 
-import {onType} from '#core/helpers.js'
+import {match} from '#core/helpers.js'
 import {Returns} from '#core/Type.js'
 
-export const plain = f => onType(
+export const plain = f => match(
    Array(f.length).fill(NumberT), Returns(NumberT, f))
 
 // Takes a behavior returning boolean, and returns a factory

src/number/relational.js

@@ -1,4 +1,4 @@
-import {onType} from '#core/helpers.js'
+import {match} from '#core/helpers.js'
 import {Returns} from '#core/Type.js'
 import {Optional} from '#core/TypePatterns.js'
 import {boolnum} from './helpers.js'
@@ -11,7 +11,7 @@ import {NumberT} from './NumberT.js'
 
 // Notice a feature of TypedDispatcher: if you specify one tolerance, you must
 // specify both.
-export const indistinguishable = onType(
+export const indistinguishable = match(
    [NumberT, NumberT, Optional([NumberT, NumberT])],
    boolnum((a, b, [tolerances = [0, 0]]) => {
       const [relTol, absTol] = tolerances
@@ -34,4 +34,4 @@ export const indistinguishable = onType(
 // Returns truthy if a (interpreted as completely precise) represents a
 // greater value than b (interpreted as completely precise). Note that even if
 // so, a and b might be indistinguishable() to some tolerances.
-export const exceeds = onType([NumberT, NumberT], boolnum((a, b) => a > b))
+export const exceeds = match([NumberT, NumberT], boolnum((a, b) => a > b))

src/number/type.js

@@ -1,13 +1,14 @@
 import {plain} from './helpers.js'
 import {BooleanT} from '#boolean/BooleanT.js'
+import {match} from '#core/helpers.js'
 import {Returns} from '#core/Type.js'
 import {NumberT} from '#number/NumberT.js'
 
 const num = f => Returns(NumberT, f)
 
-export const number = plain(a => a)
+export const number = [
-number.also(
+   plain(a => a),
    // conversions from Boolean should be consistent with one and zero:
-   BooleanT, num(p => p ? NumberT.one : NumberT.zero),
+   match(BooleanT, num(p => p ? NumberT.one : NumberT.zero)),
-   [], num(() => 0)
+   match([], num(() => 0))
-)
+]

src/number/utils.js

@@ -2,7 +2,7 @@ import {plain, boolnum} from './helpers.js'
 import {NumberT} from './NumberT.js'
 
 import {Returns} from '#core/Type.js'
-import {onType} from '#core/helpers.js'
+import {match} from '#core/helpers.js'
 
 export const clone = plain(a => a)
-export const isnan = onType(NumberT, boolnum(isNaN))
+export const isnan = match(NumberT, boolnum(isNaN))