lambda-math - npm Package Compare versions

Comparing version 0.1.1 to 0.2.0

package.json

 {
   "name": "lambda-math",
-  "version": "0.1.1",
+  "version": "0.2.0",
   "description": "Pseudo lambda expressions for JS arbitrary-precision arithmetic operations.",
@@ -5,0 +5,0 @@ "main": "src/index.js",

README.md

@@ -68,3 +68,3 @@ # Lambda math
 
-The library `lambda-math` exports the symbols `λ` and `Σ`, along with a number of mathematical functions. At the moment there are just 4 arithmetic functions available. Addition, subtraction, multiplication, and division:
+The library `lambda-math` exports the symbols `λ`, `Ω`, and `Σ`, along with a number of mathematical functions. At the moment there are just 4 arithmetic functions available. Addition, subtraction, multiplication, and division:
 
@@ -86,2 +86,4 @@ ```
 
+The function `Ω` can be used to easily index any of the results produced by the `λ` function. This is helpful when the number of invocation of `λ` is dynamic and you don't want to keep track of the index of last result.
+
 Some examples follow below to better demonstrate these concepts.
@@ -188,2 +190,51 @@
 
+If you want to quickly reference some of the latest `λ` results, but don't want to store the invocation number in a variable, `lambda-math` provides the `Ω` function. This function has two goals.
+
+Firstly, if you call it without any parameter, it will return the number of times `λ` has been called up to this point. I.e. the number of results available. For example:
+
+```
+λ(add, [1, 2])
+ (add, [3, 4])
+ (add, [5, 6])
+ (add, [7, 8]);
+
+console.log(Ω()); // 4
+```
+
+Secondly, if you pass an integer, you will get the `Nth` result from the start or from the end, depending on the sign of the integer passed. For example:
+
+```
+λ( add, [1, 2] )
+ ( add, [3, 4] )
+ ( add, [5, 6] )
+ ( add, [7, 8] )
+ ( add, [9, 10] );
+
+console.log(Ω(1).number); // 19
+console.log(Ω(2).number); // 15
+console.log(Ω(3).number); // 11
+console.log(Ω(4).number); //  7
+console.log(Ω(5).number); //  3
+```
+
+And if you pass negative integers:
+
+```
+λ( add, [1, 2] )
+ ( add, [3, 4] )
+ ( add, [5, 6] )
+ ( add, [7, 8] )
+ ( add, [9, 10] );
+
+console.log(Ω(-1).number); //  3
+console.log(Ω(-2).number); //  7
+console.log(Ω(-3).number); // 11
+console.log(Ω(-4).number); // 15
+console.log(Ω(-5).number); // 19
+```
+
+Please note, passing `0` as a parameter to `Ω` function is undefined behavior, and the library will throw an error.
+
+### Example 9
+
 Last, but not least, `λ.reset()` is available to clear all `lambda-math` state, and reset the results stack to zero.
@@ -190,0 +241,0 @@

src/index.js

@@ -1,5 +0,5 @@
-const { λ } = require('./lambda');
+const { λ, Ω } = require('./lambda');
 const { Σ } = require('./sigma');
 const { add, sub, mul, div } = require('./math');
 
-module.exports = { λ, Σ, add, sub, mul, div };
+module.exports = { λ, Ω, Σ, add, sub, mul, div };

src/lambda.js

@@ -5,2 +5,3 @@ const BigNumber = require('bignumber.js');
 const { add, sub, mul, div } = require('./math');
+const { isInteger } = require('./utils');
 
@@ -119,2 +120,26 @@ let λCallCount = -1;
 
-module.exports = { λ };
+function Ω(idx) {
+  if (typeof idx === 'undefined') {
+    return λCallCount + 1;
+  } else if (typeof idx === 'number') {
+    if (idx === 0) {
+      throw new Error('Parameter to Ω() can not be 0.');
+    }
+
+    if (!isInteger(idx)) {
+      throw new Error('Parameter to Ω() must be an integer.');
+    }
+
+    if ((idx < 0) && (Math.abs(idx) <= λCallCount + 1)) {
+      return λ[Math.abs(idx) - 1];
+    } else if ((idx > 0) && (idx <= λCallCount + 1)) {
+      return λ[λCallCount - (idx - 1)];
+    } else {
+      throw new Error('Parameter to Ω() is out of bounds.');
+    }
+  } else {
+    throw new TypeError('Parameter to Ω() should be either a number or undefined.');
+  }
+}
+
+module.exports = { λ, Ω };

src/utils.js

@@ -28,2 +28,6 @@ const BigNumber = require('bignumber.js');
 
-module.exports = { verifyFuncParams, convertFuncParams };
+function isInteger(n) {
+  return n % 1 === 0;
+}
+
+module.exports = { verifyFuncParams, convertFuncParams, isInteger };

No alert changes

Improved metrics

Total package byte prevSize

90003

increased by2.68%

Lines of code

2027

increased by1.25%

Number of lines in readme file

276

increased by22.67%

No dependency changes