siyu798 <siyu...@gmail.com> writes:
Hi!
> Is there an idiomatic/built-in way to parse double with a default
> value if there's exception?
Not that I know of.
> Currently we use a generic with-default macro to ignore exception and
> return default value as follow:
>
> (with-default 0.0 (Double. my-value))
Why a macro instead of a function?
--8<---------------cut here---------------start------------->8---
(defn parse-double [s & [d]]
(try
(Double/valueOf s)
(catch Exception _ d)))
--8<---------------cut here---------------end--------------->8---
That way, you can use it directly with higher-order functions:
;; Without default value
(map parse-double
["0" "1.5" "3.8e-1" "broken" "0x1.bP2" "Infinity" "NaN"])
==> (0.0 1.5 0.38 nil 6.75 Infinity NaN)
;; With default value 42.0
(map #(parse-double % 42.0)
["0" "1.5" "3.8e-1" "broken" "0x1.bP2" "Infinity" "NaN"])
==> (0.0 1.5 0.38 42.0 6.75 Infinity NaN)
Bye,
Tassilo
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