Core Pattern helpers

match-iz 🔥 docs

Core Pattern-helpers

• Numbers
• Strings
• Strings + Arrays
• Arrays
• Primitives
• Truthiness
• Negation
• Combinators

match-iz provides a number of composable matchers you can use to build patterns:

Numbers	Strings	Strings/Arrays	Arrays	Truthiness	Primitives	Negate	Combinators
gt(n)	startsWith('s')	includes(o)	some(...)	empty	isArray	not(...)	allOf(...)
lt(n)	endsWith('s')	-	every(...)	falsy	isDate	-	anyOf(...)
gte(n)	-	-	-	defined	isFunction	-	firstOf(...)
lte(n)	-	-	-	truthy	isNumber	-	lastOf(...)
inRange(x,y)	-	-	-	-	isPojo	-	includedIn(...)
-	-	-	-	-	isRegExp	-	hasOwn(...)
-	-	-	-	-	isString	-	-
-	-	-	-	-	instanceOf	-	-

Just import them from match-iz as you do the core library:

import { gt, lt, ...etc } from 'match-iz'

Numbers

Matchers	Meaning
gt / lt / gte / lte / inRange	number comparisons

match(5)(
  when(3)('Exactly 3'),
  when(gt(0))('Greater than 0'),
  when(gte(4))('Greater than or equal to 4'),
  when(lt(10))('Less than 10'),
  when(lte(9))('Less than or equal to 9'),
  when(inRange(5, 10))('Between 5 and 10 inclusive')
)

Strings

Matchers	Meaning
startsWith / endsWith	string comparisons

match('lorem ipsum')(
  when('lipsum')('Exactly "lipsum"'),
  when(startsWith('ip'))('Starts with "ip"'),
  when(endsWith('um'))('Ends with "um"')
)

Strings + Arrays

Helper	Meaning
includes	string/array comparisons

match('lorem ipsum')(
  when(includes('em'))('Got "em"'),
  when(includes('zap'))('Found "zap"')
)

match([1, 2, 3, 4])(
  when(includes(5))('Array has a 5'),
  when([1, 2, 3, gt(3)])('Array is [1, 2, 3, >3]')
)

Arrays

Matchers	Meaning
some / every	array item comparisons

match(array)(
  when(every(isNumber))('all items are numbers'),
  when(some(isNumber))('some items are numbers'),
  when(every({ id: isNumber }))('all items have an id property')
)

Truthiness

Matchers	Meaning
empty / defined / falsy / truthy	bottom-value comparisons

match('')(
  when(empty)(() => {
    return "It's '', {}, [], null, undefined, or NaN"
  }),
  when(defined)('Opposite of empty'),
  when(falsy)("It's falsy"),
  when(truthy)("It's truthy")
)

Primitives

Matchers	Meaning
isArray / isDate / isFunction / isNumber / isPojo / isRegExp / isString / instanceOf	primitive comparisons

match([1, 2, 3])(
  when(isArray)('Looks like an array, eh?'),
  when(instanceOf(Component))('A nice component')
)

Negation

Helper	Meaning
not	negation

match(5)(
  when(not(5))('Not a 5'),
  when(not(gte(4)))('Less than 4'),
  when(not(inRange(100, 0)))(() => {
    return 'Less than 0 or greater than 100'
  })
)

Combinators

Matchers	Meaning
allOf / anyOf / firstOf / lastOf / includedIn / hasOwn	combinators

match({ one: 1, two: 2, three: [1, 2, 'a'] })(
  when(allOf(isPojo, hasOwn('one')))(() => {
    return 'Has "one"'
  }),
  when({ one: anyOf(1, 2, 3) })(() => {
    return 'Has "one" of 1, 2, or 3'
  }),
  when({ two: includedIn(1, gt(3)) })(() => {
    return 'Has "two" with a value of 1 or >3'
  }),
  when({ three: lastOf(isString) })(() => {
    return 'Has "three" with a string value in the last position'
  })
)

match([1, 'a', 3, 4, 5, 6])(
  when(lastOf(isNumber, isString), () => {
    return 'last two items are a number and a string'
  }),
  when(firstOf(isNumber, isString), () => {
    return 'first two items are a number and a string'
  })
)