An ex'presh'n langauge.. for safe evaluation of arbitrary functionality in javascript.
npm install presh!Node.js Test Runner
!GitHub code size in bytes
An ex'presh'n langauge.. for safe evaluation of arbitrary functionality in javascript.
Highly functional, stateless, easy to add scope to, expressive, readable.
Implicit returns.
``
halve(x){ x / 2 }
halve(2) -> 1
`
Constant-only assignment.
`
x = 5 <- Yep
x = 4 <- Nope!
a = { foo: 'bar' } <- Sure.
a.foo = 'baz' <- Nope!
var, let, const <- Nope nope nope!
namedFunction(x){ ... } <- Sure!
`
Ranges.
`
[1..10] -> [1,2,3,4,5,6,7,8,9,10]
[10..1] -> [10,9,8,7,6,5,4,3,2,1]
[-2..2] -> [-2,-1,0,1,2]
`
Spread (apply, array, object)
Apply:
`
sum(...args){ fold(args (a b) { a + b }) }
sum(1 2 3 4) -> 10
`
Array:
`
[0..10] -> [0,1,2,3,4,5,6,7,8,9,10]
`
Object:
`
defaults(){{a:1 b:2}}
{...defaults() c: 3} -> { a: 1, b: 2, c: 3 }
`
Literal delete:
Object:
`
defaults(){{a:1 b:2}}
{...defaults() c: 3 delete a} -> { b: 2, c: 3 }
`
result = presh(expression, scope);
`
var presh = require('presh');
var result = presh('2 + thing', {
thing: 4
});
if(result.error){
// If the expression execution errored
console.log(result.error);
}else{
// The expression executed without error.
console.log(result.value);
}
`
npm i -g presh
presh -e '1 + 1'
Syntax
presh syntax is similar to javascript, but a little more weighted to functional programming.
Key differences from javascript:
$3
Comma's are delimiters.
// Function definition
doSomething(1 2 3){
...
}// Function call
doSomething(1 2 3)
// Array literal
[1 2 3]
$3
// Named
add(parameter1 parameter2){ parameter1 + parameter2 } // Anonymous
(parameter1 parameter2){ parameter1 + parameter2 }
$3
// From an identifier
add(1 2) // -> 3 // Anonymous
((x) {x+2}) (4) // -> 6
$3
[0..100] // -> [0,1,2,3,...,98,99,100]
$3
map([0..100] (x){x*2})// -> [0,2,4,6,...,196,198,200]