Wolfram Mathematica

9:47 AM

@b3m2a1 it seems you managed to make use of mutation handler and friends, I'm looking forward to seeing your input then :) mathematica.stackexchange.com/q/165843/5478

3 hours later…

12:29 PM

OptionQ@<|"a" -> 1, "b" -> 1|>

returns True

Is this expected?

1 hour later…

P. Fonseca

1:31 PM

@kuba interesting... I haven’t seen anything pointing in that direction...

2:04 PM

@P.Fonseca hard to complain since it is undocumented but still

3 hours later…

5:31 PM

@Kuba - for your undocumented functions post:
```
In[1]:= (* weak hash maps in WL *)
$HistoryLength = 0

Out[1]= 0

In[2]:= store = Language`NewExpressionStore["label"]

Out[2]= Language`ExpressionStore["label"]

(* x is some l-value, pointing to an expression *)

In[3]:= x = f[2]

Out[3]= f[2]

(* store any key value pairs in the expression store *)

In[4]:= store["put"[x, "key", value]]

(* you can retrieve the values *)

In[5]:= store["get"[x, "key"]]

Out[5]= value

(* caching is done by identity for the expression, so two identical \

I find this to be incredibly useful for caching

halirutan

6:25 PM

@JasonB. Tripple backticks don't work. If you want to post a code-block, make it a new message and paste the code in, mark all and press Ctrl+K to indent it with 4 spaces.

In[1]:= (* weak hash maps in WL *)
$HistoryLength = 0

Out[1]= 0

In[2]:= store = Language`NewExpressionStore["label"]

Out[2]= Language`ExpressionStore["label"]

(* x is some l-value, pointing to an expression *)

In[3]:= x = f[2]

Out[3]= f[2]

(* store any key value pairs in the expression store *)

In[4]:= store["put"[x, "key", value]]

(* you can retrieve the values *)

(ah, you don't need to mark all. Just press Ctrl+K)

1 hour later…

7:31 PM

@JasonB. feel free to elaborate in an answer, unless that is against rules

I don't really know what the rules are, so I just put it here

Perhaps it's lazy of me, but I was assuming @b3m2a1 might see the code above and recognize how useful it is, and post an answer :-)

Say you have a HoldFirst function that takes a function (and its parameters) as the first argument (foo_) and you want to extra parts of the parameter sequence of foo in the function. Is it better to use Unevaluated[foo][[3]] or Hold[foo][[1,3]]

7:47 PM

In[4]:= Attributes[func] = {HoldFirst}
func[foo : _[args__]] := {args}

Out[4]= {HoldFirst}

In[6]:= func[Graph[{1, 2, 3}, {1 -> 2}]]

Out[6]= {{1, 2, 3}, {1 -> 2}}

@JasonB. Yes. I see. Thanks

@Edmund ^ is how I normally do it, but from your choices I can't get the Hold version to work, but the Unevaluated one works

@JasonB. So this should work as well monitorParallel[pm : ParallelMap[args__]]:=

Yes, that should prevent ParallelMap from evaluating

and allow access to its arguments

@JasonB. Great. thanks