Created
September 13, 2012 22:59
-
-
Save juandopazo/3718393 to your computer and use it in GitHub Desktop.
Why I want ES.next yesterday
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
// some code I'm writing... | |
class Matrix { | |
/* ... */ | |
transpose() { | |
var [n, m] = this.size(), | |
rows = this.rows, | |
result = [], | |
i = 0, j = 0; | |
for (j = 0; j < m; j++) { | |
result[j] = []; | |
for (i = 0; i < n; i++) { | |
result[j][i] = rows[i][j]; | |
} | |
} | |
return new Matrix(...result); | |
} | |
svd() { | |
let A = this.transpose().x(this), | |
[n, m] = this.size(), | |
S = Matrix.Zeros(n, m); | |
A.eigenvalues() | |
.sort((a, b) => b - a}) | |
.map(Math.sqrt) | |
.forEach((val, i) => S.rows[i][i] = val); | |
/* ... */ |
I've been avoiding let
because Traceur uses try...catch
when you use it inside blocks and that's a performance killer. For example this:
transpose() {
var [n, m] = this.size(),
rows = this.rows,
result = [],
j = 0;
for (j = 0; j < m; j++) {
result[j] = [];
for (let i = 0; i < n; i++) {
result[j][i] = rows[i][j];
}
}
return new Matrix(...result);
}
...turns into:
transpose: function() {
var destructuring$m$n = this.size(), n = destructuring$m$n[0], m = destructuring$m$n[1], rows = this.rows, result =[], j = 0;
for(j = 0; j < m; j ++) {
result[j]=[];
{
try {
throw undefined;
} catch($i) {
$i = 0;
for(; $i < n; $i ++) {
try {
throw undefined;
} catch(i) {
i = $i;
try {
result[j][i]= rows[i][j];
} finally {
$i = i;
}
}
}
}
}
}
return traceur.runtime.spreadNew(Matrix,[true, result]);
}
When you use let
in the top scope of a function it just turns it into a var
so in this case it works ok.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Possibility: replace
var
withlet
.