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7
docs/EffectfulEvents.md
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@ -108,7 +108,7 @@ And here's more carnage:
``` ```
Again, this approach will work. But that dirty great big side-effect doesn't come Again, this approach will work. But that dirty great big side-effect doesn't come
for free. Its like a muddy monster truck has shown up in our field of white tulips. for free. It's like a muddy monster truck has shown up in our field of white tulips.
### Bad, Why? ### Bad, Why?
@ -353,7 +353,7 @@ data from arguments.
`-db` handlers and `-fx` handlers are conceptually the same. They only differ numerically. `-db` handlers and `-fx` handlers are conceptually the same. They only differ numerically.
`-db` handlers take ONE coeeffect called `db`, and they return only ONE effect (db again). `-db` handlers take ONE coeffect called `db`, and they return only ONE effect (db again).
Whereas `-fx` handlers take potentially MANY coeffects (a map of them) and they return Whereas `-fx` handlers take potentially MANY coeffects (a map of them) and they return
potentially MANY effects (a map of them). So, One vs Many. potentially MANY effects (a map of them). So, One vs Many.
@ -381,7 +381,7 @@ can. The `-fx` version is more flexible, so it will sometimes have its place.
90% of the time, simple `-db` handlers are the right tool to use. 90% of the time, simple `-db` handlers are the right tool to use.
But about 10% of the time, our handlers need additional inputs (coeffecs) or they need to But about 10% of the time, our handlers need additional inputs (coeffects) or they need to
cause additional side-effects (effects). That's when you reach for `-fx` handlers. cause additional side-effects (effects). That's when you reach for `-fx` handlers.
`-fx` handlers allow us to return effects, declaratively in data. `-fx` handlers allow us to return effects, declaratively in data.
@ -389,4 +389,3 @@ cause additional side-effects (effects). That's when you reach for `-fx` handle
In the next tutorial, we'll shine a light on `interceptors` which are In the next tutorial, we'll shine a light on `interceptors` which are
the mechanism by which event handlers are executed. That knowledge will give us a springboard the mechanism by which event handlers are executed. That knowledge will give us a springboard
to then, as a next step, better understand coeffects and effects. We'll soon be writing our own. to then, as a next step, better understand coeffects and effects. We'll soon be writing our own.

12
docs/Interceptors.md
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@ -36,7 +36,7 @@ Flowing" story promoted by re-frame.
So, you'll want to use Interceptors because they solve problems, and help you to write nice code. So, you'll want to use Interceptors because they solve problems, and help you to write nice code.
__Second__, under the covers, Interceptors provide the mechanism by which __Second__, under the covers, Interceptors provide the mechanism by which
event handlers are executed (when you `dispatch`). You they are central concept. event handlers are executed (when you `dispatch`). They are a central concept.
### What Do Interceptors Do? ### What Do Interceptors Do?
@ -45,7 +45,7 @@ They wrap.
Specifically, they wrap event handlers. Specifically, they wrap event handlers.
Imagine your event handler is like a piece of ham. An interceptor would be Imagine your event handler is like a piece of ham. An interceptor would be
like bread either side of your ham, which makes a sandwich. like bread on either side of your ham, which makes a sandwich.
And two Interceptors, in a chain, would be like you put another And two Interceptors, in a chain, would be like you put another
pair of bread slices around the outside of the existing sandwich to make pair of bread slices around the outside of the existing sandwich to make
@ -154,7 +154,7 @@ That's it. That's how an event gets handled.
Some data called a `context` is threaded through all the calls. Some data called a `context` is threaded through all the calls.
This value is passed as the argument to every `:before` and `:after` This value is passed as the argument to every `:before` and `:after`
function and they returned it, possibly modified. function and it is returned by each function, possibly modified.
A `context` is a map with this structure: A `context` is a map with this structure:
```clj ```clj
@ -189,7 +189,7 @@ DataScript connection. Interceptors can build up `:coeffects`, via their
Equally, some interceptors in the chain will have `:after` functions Equally, some interceptors in the chain will have `:after` functions
which process the side effects accumulated into `:effects` which process the side effects accumulated into `:effects`
including but, not limited to, updates to app-db. including, but not limited to, updates to app-db.
### Self Modifying ### Self Modifying
@ -223,7 +223,7 @@ If our components did this:
We'd have to write this handler: We'd have to write this handler:
```clj ```clj
(def-event-db (reg-event-db
:delete-item :delete-item
(fn (fn
[db [_ key-to-delete]] ;; <---- Arrgggghhh underscore [db [_ key-to-delete]] ;; <---- Arrgggghhh underscore
@ -239,7 +239,7 @@ What a relief it would be to get rid of it, but how? We'll write an interceptor:
Once we have written `trim-event`, our registration will change to look like this: Once we have written `trim-event`, our registration will change to look like this:
```clj ```clj
(def-event-db (reg-event-db
:delete-item :delete-item
[trim-event] ;; <--- interceptor added [trim-event] ;; <--- interceptor added
(fn (fn

6
docs/coeffects.md
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@ -121,7 +121,7 @@ to our event handler (`cofx`).
### `inject-cofx` ### `inject-cofx`
`inject-cofx` is part of re-frame API. `inject-cofx` is part of the re-frame API.
It is a function which returns an Interceptor whose `:before` function loads It is a function which returns an Interceptor whose `:before` function loads
a key/value pair into a `context's` `:coeffect` map. a key/value pair into a `context's` `:coeffect` map.
@ -159,7 +159,7 @@ Each `cofx-id` requires a different action.
This function is also part of the re-frame API. This function is also part of the re-frame API.
It allows you associate a`cofx-id` (like `:now` or `:local-store`) with a It allows you to associate a`cofx-id` (like `:now` or `:local-store`) with a
handler function that injects the right key/value pair. handler function that injects the right key/value pair.
The function you register will be passed two arguments: The function you register will be passed two arguments:
@ -227,7 +227,7 @@ registration functions and have them auto insert the DataScript connection.
### Testing ### Testing
During testing, you may want to stub out certain coeffets. During testing, you may want to stub out certain coeffects.
You may, for example, want to test that an event handler works You may, for example, want to test that an event handler works
using a specific `now`, not a true random number. using a specific `now`, not a true random number.