feat(clamp): add function

.eslintrc

@@ -107,7 +107,7 @@
     "no-whitespace-before-property": 2,
     "no-with": 2,
     "one-var": 2,
-    "operator-linebreak": [2, "after", { "overrides": { "?": "before", ":": "before" } }],
+    "operator-linebreak": [0, "after", { "overrides": { "?": "before", ":": "before" } }],
     "padded-blocks": [2, "never"],
     "quotes": [2, "single", "avoid-escape"],
     "semi": [2, "never"],

src/bundles/index.js

@@ -5,6 +5,7 @@ export { default as any }         from '../any'
 export { default as append }      from '../append'
 export { default as assoc }       from '../assoc'
 export { default as chain }       from '../chain'
+export { default as clamp }       from '../clamp'
 export { default as concat }      from '../concat'
 export { default as cond }        from '../cond'
 export { default as contains }    from '../contains'

src/clamp.js

@@ -0,0 +1,18 @@
+import _curry3 from './internal/_curry3'
+
+/**
+ * @name clamp
+ * @signature Number -> Number -> Number -> Number
+ * @since v0.18.0
+ * @description
+ * Restricts a value to a given range (inclusive).
+ * @example
+ * clamp(1, 10, 5)  // => 5
+ * clamp(1, 10, -5) // => 1
+ * clamp(1, 10, 15) // => 15
+ */
+export default _curry3(function clamp (lower, upper, value) {
+  return value < lower ? lower :
+         value > upper ? upper :
+         value
+})

tests/clamp.spec.js

@@ -0,0 +1,23 @@
+const test      = require('ava')
+    , { clamp } = require('../dist/redash')
+
+test('properly reports its arity (is ternary)', (t) => {
+  t.is(clamp.length, 3)
+})
+
+test('is curried', (t) => {
+  t.is(typeof clamp(1), 'function')
+  t.is(typeof clamp(1, 10), 'function')
+})
+
+test('restricts values to the lower bound', (t) => {
+  t.is(clamp(1, 10, -5), 1)
+})
+
+test('restricts values to the upper bound', (t) => {
+  t.is(clamp(1, 10, 15), 10)
+})
+
+test('allows values between the lower and upper bound', (t) => {
+  t.is(clamp(1, 10, 5), 5)
+})