1.7.3 • Published 4 years ago
markwylde-presh v1.7.3
Presh
An ex'presh'n langauge.. for safe evaluation of arbitrary functionality in javascript.
Goals
Highly functional, stateless, easy to add scope to, expressive, readable.
Try
features
Implicit returns.
halve(x){ x / 2 }
halve(2) -> 1
No assignment.
x = 5 <- 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 }
usage
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);
}
With cli
You can use the cli to run a script:
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:
No commas
// Function definition
doSomething(1 2 3){
...
}
// Function call
doSomething(1 2 3)
// Array literal
[1 2 3]
Function Expression
// Named
add(parameter1 parameter2){ parameter1 + parameter2 }
// Anonymous
(parameter1 parameter2){ parameter1 + parameter2 }
Function Execution
// From an identifier
add(1 2) // -> 3
// Anonymous
((x) {x+2}) (4) // -> 6
Range
[0..100] // -> [0,1,2,3,...,98,99,100]
Looping
map([0..100] (x){x*2})// -> [0,2,4,6,...,196,198,200]
1.7.3
4 years ago