Helpful combinators
For the non-pedants, a combinator is basically just a function with no free variables.
For the non-pedants, "no free variables" means that the combinator does not have dependencies
on things outside the function (e.g. it only depends on the function parameters).
A strict definition of combinators requires functions as input parameters, but I loosen that here.
That definition really only serves mathematical modeling of state in pure functional terms
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Methods
(static) constant(k) → {function}
Ignores its parameters, and instead always returns a constant value
Parameters:
| Name | Type | Description |
|---|---|---|
k |
Object | The constant to return |
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Returns:
- A function that will always return the constant
- Type
- function
(static) identity(i) → {Object}
Returns what was passed in unchanged, occasionally useful as the default transformation function
to avoid special case logic
Parameters:
| Name | Type | Description |
|---|---|---|
i |
Object | The input |
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Returns:
Exactly what was passed in
- Type
- Object
(static) noop()
A function that does nothing, occasionally useful to avoid special case logic
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(inner) compose(…args) → {function}
Composes two or more functions
Parameters:
| Name | Type | Attributes | Description |
|---|---|---|---|
args |
function |
<repeatable> |
The functions to compose |
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Returns:
A single function that represents the composition of the functions provided
- Type
- function
Example
function increment (i) { return i + 1; }
function double (i) { return i * 2; }
function triple (i) { return i * 3; }
combinators.compose(increment, double, triple)(1); // returns 7(inner) curry(fn, …args) → {function}
Curries a function parameters, which is to say that it returns a function with reduced arity.
Parameters:
| Name | Type | Attributes | Description |
|---|---|---|---|
fn |
function | The function to curry |
|
args |
* |
<repeatable> |
The arguments to curry |
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Returns:
- Type
- function
Example
function sum (x, y) { return x + y; }
curry(sum, 1)(2); // returns 3
curry(sum, 1, 2)(); // returns 3