add walkthrough file #65
Conversation
| @@ -0,0 +1,262 @@ | |||
| (require '[state-flow.core :refer [flow run]] | |||
There was a problem hiding this comment.
This is in a .repl file instead of .clj because the intent is to evaluate expressions one at a time, not load up a namespace.
| ;; primitives. Here's another primitive, which returns a specified | ||
| ;; value without modifying the internal state: | ||
|
|
||
| (run (state/return {:count 37}) {:count 0}) |
dchelimsky
force-pushed
the
dc/walkthrough
branch
2 times, most recently
from
e3d63d7 to
44fcf76
Compare
| (state/wrap-fn #(fetch-users db)) | ||
| #{{:name "Philip"}})) ;; <- different spelling | ||
| {:db (atom {:users #{}})}) | ||
| ;; => #<Pair [#{{:name "Phillip"}} {:db #atom[{:users #{{:name "Phillip"}}} 0x4c2a27a6]}]> |
There was a problem hiding this comment.
I added #66 to sugest that we include the failure information below in the return value above
There was a problem hiding this comment.
👏
I like it and learned a bit about :mfn and such, which I had sorta ignored until now :)
One thing I wonder about is we have a few docs kicking around with examples of how to interact with state-flow (I think I wrote two different ones). Do you think this one could replace those?
doc/walkthrough.repl
Outdated
| ;; | ||
| ;; - A monad is a wrapper around a function. | ||
| ;; - A state monad is a monad whose function is a function of | ||
| ;; some mutable state, which is managed for you by a runner. |
There was a problem hiding this comment.
maybe is a monad whose function is one over some mutable state? The double occurrence of function is tripping me up a little
There was a problem hiding this comment.
Updated using of (but removing the redundancy).
| ;; - :state-context is a reference to mutable state, which will be | ||
| ;; managed by state-flow. | ||
| ;; | ||
| ;; The :mfn of a state monad is a function of state, which returns |
There was a problem hiding this comment.
for some reason I want to see function over state, though I dunno if that is at all more standard, let alone correct
There was a problem hiding this comment.
I think this is subjective (incorrect to call it incorrect or non-standard). That said, I think of closures as closing over bindings and functions being of their arguments. Does that make sense to you?
|
|
||
| (state/get) | ||
| ;; => #cats.monad.state.State{:mfn #object[...], | ||
| ;; :state-context #<State-E>} |
There was a problem hiding this comment.
I wonder if there is a better way to represent the state context for printing. LikeState-E is quiet cryptic
There was a problem hiding this comment.
Agreed. Looking into it.
There was a problem hiding this comment.
That's on us:
state-flow/src/state_flow/state.clj
Lines 55 to 57 in 210798c
Without that, we get this:
(state/get)
;; => {:mfn #function[state-flow.state/reify--15501/fn--15509],
;; :state-context #object[state_flow.state$reify__15501 0x68fabfd8 "state_flow.state$reify__15501@68fabfd8"]}That might be a better option for now. WDYT?
There was a problem hiding this comment.
/cc @sovelten - got an opinion on this from afar?
doc/walkthrough.repl
Outdated
| ;; ------------------------------------------- | ||
|
|
||
| ;; state-flow is implemented using a state monad. If you're already | ||
| ;; familiar with monads, great! If not, don't worrry. We'll explain |
Links? I think this replaces the introductory material, but we still need more advanced material, which might make sense to be where you have examples already with a reference to the walkthrough. |
dchelimsky
force-pushed
the
dc/walkthrough
branch
from
44fcf76 to
204b25d
Compare
dchelimsky
force-pushed
the
dc/walkthrough
branch
from
204b25d to
9fe96ed
Compare
Our language about the state monad thus far has been "pay no attention the man behind the curtain", but I think it's actually helpful to explain the mechanics. I've found it especially confusing that we've adopted the term "flow" to talk about individual steps.
This PR includes a walkthrough that introduces the basic mechanics of the state monad and builds on that.