There are a couple of tools I set up here: some let debugging
functions, and a neat library called Spyscope.
Due to how these are set up in your local ~/.lein profile, they're pervasively and conveniently available to you at the repl.
There are two variants: a simpler "debug let", and a richer "pprint let".
If you have a complex let you want to inspect:
(let [indices (get-indices-from-somewhere)
clean-indices (filter clean-idx? indices)
other-data (retrieve-data clean-indices)]
(map :result other-data))instead of doing the old _ (log/debug x) trick
(let [indices (get-indices-from-somewhere)
_ (log/debug "indices" indices)
clean-indices (filter clean-idx? indices)
_ (log/debug "clean-indices" clean-indices)
other-data (retrieve-data clean-indices)
_ (log/debug "other-data" other-data)]
(map :result other-data)) 02:23:32 DEBUG [foo.core:74] - indices [{:idx 1, :state :ok} {:idx 4, :state :error} {:idx 22, :state :ok} {:idx 29, :state :ok}]
02:23:32 DEBUG [foo.core:76] - clean-indices ({:idx 1, :state :ok} {:idx 22, :state :ok} {:idx 29, :state :ok})
02:23:32 DEBUG [foo.core:78] - other-data ({:result {:town "Wimborne", :alternate "Bircham", :index 1}} {:result {:town "Erith", :alternate "Taplow", :index 22}} {:result {:town "Wimborne", :alternate "Vauxhall", :index 29}})
you can just replace the let with either dlet for a quick
printout:
(user/dlet [indices (get-indices-from-somewhere)
clean-indices (filter clean-idx? indices)
other-data (retrieve-data clean-indices)]
(map :result other-data))indices : [{:idx 1, :state :ok} {:idx 4, :state :error} {:idx 22, :state :ok} {:idx 29, :state :ok}]
clean-indices : ({:idx 1, :state :ok} {:idx 22, :state :ok} {:idx 29, :state :ok})
other-data : ({:result {:town Calthorpe, :alternate Wrentham, :index 1}} {:result {:town Fairview, :alternate Wembley, :index 22}} {:result {:town Dovercourt, :alternate Vauxhall, :index 29}})
or with plet for a more detailed view:
(user/plet [indices (get-indices-from-somewhere)
clean-indices (filter clean-idx? indices)
other-data (retrieve-data clean-indices)]
(map :result other-data)){indices foo.core/indices,
clean-indices
({:idx 1, :state :ok} {:idx 22, :state :ok} {:idx 29, :state :ok}),
other-data
({:result {:town "Brocket", :alternate "Chailey", :index 1}}
{:result {:town "Erith", :alternate "Amesbury", :index 22}}
{:result
{:town "Drayton Valley", :alternate "Torrington", :index 29}})}
I forget exactly where I found these now, they've been in my profile for so long.
Spyscope is a super-quick way of typing a bit of code to inspect some data. Same example as above, say you just wanted to look at the value of other-data before being mapped, and the result of that map:
(let [indices (get-indices-from-somewhere)
clean-indices (filter clean-idx? indices)
other-data (retrieve-data clean-indices)]
#spy/p (map :result #spy/p other-data))This shows up in the repl:
({:result {:alternate "Taplow", :index 1, :town "Fairview"}}
{:result {:alternate "Bowden", :index 22, :town "Chigwell"}}
{:result {:alternate "Hinton", :index 29, :town "Erith"}})
({:alternate "Taplow", :index 1, :town "Fairview"}
{:alternate "Bowden", :index 22, :town "Chigwell"}
{:alternate "Hinton", :index 29, :town "Erith"})
Magic.
Spyscope has three "functions", #spy/p for a quick printout,
#spy/d for a more detailed debugging view with stacktrace and other
cool stuff, and #spy/t for even more general purpose tracing.
Right now, to get Spyscope working with Clojure 1.9, you need to clone
the repo, lein install it, and depend on the
[spyscope "0.1.7-SNAPSHOT"]
dependency coordinate. Hopefully a new release is
published to Clojars soon.