GitBook: [master] 31 pages and one asset modified

README.md

@@ -4,5 +4,3 @@
 
 In addition to the language specification, Aqua provides a compiler, intermediate representation \(AIR\) and an execution stack, Aqua VM.
 
-
-

language/basics.md

@@ -9,17 +9,17 @@ func foo(): -- Comments are allowed almost everywhere
   bar(5)
 ```
 
-Values in Aqua have types, which are designated by a colon, `:`,  as seen in function signature below. The type of a return, which is yielded when a function is executed, is denoted by an arrow pointing to the right `->` , whereas yielding is denoted by an arrow pointing to the left `<-`.
+Values in Aqua have types, which are designated by a colon, `:`, as seen in function signature below. The type of a return, which is yielded when a function is executed, is denoted by an arrow pointing to the right `->` , whereas yielding is denoted by an arrow pointing to the left `<-`.
 
 ```text
 -- Define a function that yields a string
 func bar(arg: i16) -> string:
   -- Call a function
   smth(arg)
-  
+
   -- Yield a value from a function
   x <- smth(arg)
-  
+
   -- Return a yielded results from a function
   <- "return literal"
 ```
@@ -52,5 +52,3 @@ Reference:
 
 * [Expressions](expressions/)
 
-
-

language/expressions/functions.md

@@ -16,7 +16,7 @@ service MySrv:
 
 func do_something(): -- arrow of type: -> ()
   MySrv "srv id"
-  MySrv.foo()  
+  MySrv.foo()
 ```
 
 * list all expressions

language/expressions/header.md

@@ -1,6 +1,6 @@
 # Header
 
-### Header expressions
+## Header expressions
 
 `import`
 
@@ -10,7 +10,7 @@ The `import` expression brings everything defined within the imported file into
 import "path/to/file.aqua"
 ```
 
-The to be imported file path is first resolved relative to the source file path followed by checking for an  `-imports` directories.
+The to be imported file path is first resolved relative to the source file path followed by checking for an `-imports` directories.
 
 See [Imports & Exports](../statements-1.md) for details.
 

language/expressions/overrideable-constants.md

@@ -4,8 +4,6 @@ description: Static configuration pieces that affect compilation
 
 # Overrideable constants
 
-
-
 `const`
 
 Constant definition.

language/expressions/services.md

@@ -14,7 +14,7 @@ Services that are a part of the protocol, i.e. are available from the peer node,
 service Peer("peer"):
   foo() -- no arguments, no return
   bar(i: bool) -> bool
-  
+
 func usePeer() -> bool:
   Peer.foo() -- results in a call of service "peer", function "foo", on current peer ID
   z <- Peer.bar(true)
@@ -27,7 +27,7 @@ Example of a custom service:
 service MyService:
   foo()
   bar(i: bool, z: i32) -> string
-  
+
 func useMyService(k: i32) -> string:
   -- Need to tell the compiler what does "my service" mean in this scope
   MyService "my service id"
@@ -36,7 +36,7 @@ func useMyService(k: i32) -> string:
     -- Need to redefine MyService in scope of this peer as well
     MyService "another service id"
     z <- MyService.bar(false, k)
-  <- z  
+  <- z
 ```
 
 Service definitions have types. Type of a service is a product type of arrows. See [Types](../types.md#type-of-a-service-and-a-file).

language/topology.md

@@ -4,12 +4,11 @@ description: Define where the code is to be executed and how to get there
 
 # Topology
 
+Aqua lets developers to describe the whole distributed workflow in a single script, link data, recover from errors, implement complex patterns like backpressure, and more. Hence, topology is at the heart of Aqua.
 
-Aqua lets developers to describe the whole distributed workflow in a single script, link data, recover from errors, implement complex patterns like backpressure, and more. Hence,  topology is at the heart of Aqua. 
+Topology in Aqua is declarative: You just need to say where a piece of code must be executed, on what peer, and optionally how to get there. he Aqua compiler will add all the required network hops.
 
-Topology in Aqua is declarative:  You just need to say where a piece of code must be executed, on what peer, and optionally how to get there. he Aqua compiler will add all the required network hops.
-
-### On expression
+## On expression
 
 `on` expression moves execution to the specified peer:
 
@@ -28,15 +27,15 @@ on myPeer:
   baz()
 ```
 
-### `%init_peer_id%`
+## `%init_peer_id%`
 
-There is one custom peer ID that is always in scope: `%init_peer_id%`. It points to the peer that initiated this request. 
+There is one custom peer ID that is always in scope: `%init_peer_id%`. It points to the peer that initiated this request.
 
 {% hint style="warning" %}
 Using `on %init_peer_id%` is an anti-pattern: There is no way to ensure that init peer is accessible from the currently used part of the network.
 {% endhint %}
 
-### More complex scenarios
+## More complex scenarios
 
 Consider this example:
 
@@ -44,16 +43,16 @@ Consider this example:
 func foo():
   on "peer foo":
     do_foo()
-    
+
 func bar(i: i32):
   do_bar()
-  
+
 func baz():
   bar(1)
   on "peer baz":
     foo()
     bar(2)
-  bar(3)            
+  bar(3)
 ```
 
 Take a minute to think about:
@@ -70,7 +69,7 @@ Declarative topology definition always works the same way.
 * `bar(2)` is executed on `"peer baz"`, despite the fact that foo does topologic transition. `bar(2)` is in the scope of `on "peer baz"`, so it will be executed there
 * `bar(3)` is executed where `bar(1)` was: in the root scope of `baz`, wherever it was called from
 
-### Accessing peers `via` other peers
+## Accessing peers `via` other peers
 
 In a distributed network it is quite common that a peer is not directly accessible. For example, a browser has no public network interface and you cannot open a socket to a browser at will. Such constraints warrant a `relay` pattern: there should be a well-connected peer that relays requests from a peer to the network and vice versa.
 
@@ -81,12 +80,12 @@ Relays are handled with `via`:
 -- the compiler will add an additional hop to some relay
 on "some peer" via "some relay":
   foo()
-  
+
 -- More complex path: first go to relay2, then to relay1,
 -- then to peer. When going out of peer, do it in reverse  
 on "peer" via relay1 via relay2:
   foo()
-  
+
 -- You can pass any collection of strings to relay,
 -- and it will go through it if it's defined,
 -- or directly if not  
@@ -137,7 +136,7 @@ foo()
 
 When the `on` scope is ended, it does not affect any further topology moves. Until you stop indentation, `on` affects the topology and may add additional topology moves, which means more roundtrips and unnecessary latency.
 
-### Callbacks
+## Callbacks
 
 What if you want to return something to the initial peer? For example, implement a request-response pattern. Or send a bunch of requests to different peers, and render responses as they come, in any order.
 
@@ -150,7 +149,7 @@ func run(updateModel: Model -> (), logMessage: string -> ()):
     updateModel(m)
   par on "other peer":
     x <- getMessage()
-    logMessage(x)  
+    logMessage(x)
 ```
 
 Callbacks have the [arrow type](types.md#arrow-types).
@@ -161,15 +160,15 @@ If you pass just ordinary functions as arrow-type arguments, they will work as i
 func foo():
   on "peer 1":
     doFoo()
-    
+
 func bar(cb: -> ()):
   on "peer2":
     cb()
-    
+
 func baz():
   -- foo will go to peer 1
   -- bar will go to peer 2
-  bar(foo)            
+  bar(foo)
 ```
 
 If you pass a service call as a callback, it will be executed locally on the node where you called it. That might change.
@@ -192,7 +191,7 @@ func baz():
 Passing service function calls as arguments is very fragile as it does not track that a service is resolved in the scope of the call. Abilities variance may fix that.
 {% endhint %}
 
-### Parallel execution and topology
+## Parallel execution and topology
 
 When blocks are executed in parallel, it is not always necessary to resolve the topology to get to the next peer. The compiler will add topologic hops from the par branch only if data defined in that branch is used down the flow.
 
@@ -200,5 +199,3 @@ When blocks are executed in parallel, it is not always necessary to resolve the
 What if all branches do not return? Execution will halt. Be careful, use `co` if you don't care about the returned data.
 {% endhint %}
 
-
-

language/types.md

@@ -1,6 +1,6 @@
 # Types
 
-### Scalars
+## Scalars
 
 Scalar types follow the Wasm IT notation.
 
@@ -12,24 +12,24 @@ Scalar types follow the Wasm IT notation.
 * Records \(product type\): see below
 * Arrays: see Collection Types below
 
-### Literals
+## Literals
 
 You can pass booleans \(true, false\), numbers, double-quoted strings as literals.
 
-### Products
+## Products
 
 ```python
 data ProductName:
   field_name: string
-  
+
 data OtherProduct:
   product: ProductName
-  flag: bool  
+  flag: bool
 ```
 
-Fields are accessible with the  dot operator `.` ,  e.g. `product.field`.
+Fields are accessible with the dot operator `.` , e.g. `product.field`.
 
-### Collection Types
+## Collection Types
 
 Aqua has three different types with variable length, denoted by quantifiers `[]`, `*`, and `?`.
 
@@ -41,7 +41,6 @@ Appendable collection with 0..N values: `*`
 
 Any data type can be prepended with a quantifier, e.g. `*u32`, `[][]string`, `?ProductType` are all correct type specifications.
 
-
 You can access a distinct value of a collection with `!` operator, optionally followed by an index.
 
 Examples:
@@ -60,7 +59,7 @@ maybe_value: ?string
 value = maybe_value!
 ```
 
-### Arrow Types
+## Arrow Types
 
 Every function has an arrow type that maps a list of input types to an optional output type.
 
@@ -82,7 +81,7 @@ arrow()
 x <- arrow()
 ```
 
-### Type Alias
+## Type Alias
 
 For convenience, you can alias a type:
 
@@ -90,13 +89,12 @@ For convenience, you can alias a type:
 alias MyAlias = ?string
 ```
 
-### Type Variance
+## Type Variance
 
 Aqua is made for composing data on the open network. That means that you want to compose things if they do compose, even if you don't control its source code.
 
 Therefore Aqua follows the structural typing paradigm: if a type contains all the expected data, then it fits. For example, you can pass `u8` in place of `u16` or `i16`. Or `?bool` in place of `[]bool`. Or `*string` instead of `?string` or `[]string`. The same holds for products.
 
-
 For arrow types, Aqua checks the variance on arguments and contravariance on the return type.
 
 ```text
@@ -130,17 +128,17 @@ bar(foo4)
 
 Arrow type `A: D -> C` is a subtype of `A1: D1 -> C1`, if `D1` is a subtype of `D` and `C` is a subtype of `C1`.
 
-### Type Of A Service And A File
+## Type Of A Service And A File
 
 A service type is a product of arrows.
 
 ```text
 service MyService:
   foo(arg: string) -> bool
-  
+
 -- type of this service is:
 data MyServiceType:
-  foo: string -> bool  
+  foo: string -> bool
 ```
 
 The file is a product of all defined constants and functions \(treated as arrows\). Type definitions in the file do not go to the file type.
@@ -150,16 +148,14 @@ The file is a product of all defined constants and functions \(treated as arrows
 
 func foo(arg: string) -> bool:
   ...
-  
+
 const flag ?= true  
 
 -- type of MyFile.aqua
 data MyServiceType:
   foo: string -> bool
-  flag: bool  
+  flag: bool
 ```
 
 {% embed url="https://github.com/fluencelabs/aqua/blob/main/types/src/main/scala/aqua/types/Type.scala" caption="See the types system implementation" %}
 
-
-

language/variables.md

@@ -18,7 +18,7 @@ on "peer 1":
 
 More on that in the Security section. Now let's see how we can work with values inside the language.
 
-### Arguments
+## Arguments
 
 Function arguments are available within the whole function body.
 
@@ -26,14 +26,14 @@ Function arguments are available within the whole function body.
 func foo(arg: i32, log: string -> ()):
   -- Use data arguments
   bar(arg)
-  
+
   -- Arguments can have arrow type and be used as strings
   log("Wrote arg to responses")
 ```
 
-### Return values
+## Return values
 
-You can assign results of an arrow call to a name, and use this returned value in the code below. 
+You can assign results of an arrow call to a name, and use this returned value in the code below.
 
 ```text
 -- Imagine a Stringify service that's always available
@@ -47,7 +47,7 @@ func bar(arg: i32) -> string:
   -- Starting from there, you can use x
   -- Pass x out of the function scope as the return value
   <- x
-  
+
 
 func foo(arg: i32, log: *string):
   -- Use bar to convert arg to string, push that string
@@ -55,7 +55,7 @@ func foo(arg: i32, log: *string):
   log <- bar(arg)
 ```
 
-### Literals
+## Literals
 
 Aqua supports just a few literals: numbers, quoted strings, booleans. You [cannot init a structure](https://github.com/fluencelabs/aqua/issues/167) in Aqua, only obtain it as a result of a function call.
 
@@ -67,7 +67,7 @@ foo("double quoted string literal")
 -- Booleans are true or false
 if x == false:
   foo("false is a literal")
-  
+
 -- Numbers are different
 -- Any number:
 bar(1)  
@@ -79,9 +79,9 @@ bar(-1)
 bar(-0.2)
 ```
 
-### Getters
+## Getters
 
-In Aqua, you can use a getter to peak into a field of a product or indexed element in an array. 
+In Aqua, you can use a getter to peak into a field of a product or indexed element in an array.
 
 ```text
 data Sub:
@@ -91,7 +91,7 @@ data Example:
   field: u32
   arr: []Sub
   child: Sub
-  
+
 func foo(e: Example):
   bar(e.field) -- u32
   bar(e.child) -- Sub
@@ -100,14 +100,13 @@ func foo(e: Example):
   bar(e.arr!) -- gets the 0 element
   bar(e.arr!.sub) -- string
   bar(e.arr!2) -- gets the 2nd element
-  bar(e.arr!2.sub) -- string   
+  bar(e.arr!2.sub) -- string
 ```
 
 Note that the `!` operator may fail or halt:
 
-* If it is called on an immutable collection, it will fail if the collection is shorter and has no given index; you can handle the error with [try](operators/conditional.md#try) or [otherwise](operators/conditional.md#otherwise).
-* If it is called on an appendable stream, it will wait for some parallel append operation to fulfill, see [Join behavior](operators/parallel.md#join-behavior).
-
+* If it is called on an immutable collection, it will fail if the collection is shorter and has no given index; you can handle the error with [try](https://github.com/fluencelabs/aqua-book/tree/4177e00f9313f0e1eb0a60015e1c19a956c065bd/language/operators/conditional.md#try) or [otherwise](https://github.com/fluencelabs/aqua-book/tree/4177e00f9313f0e1eb0a60015e1c19a956c065bd/language/operators/conditional.md#otherwise).
+* If it is called on an appendable stream, it will wait for some parallel append operation to fulfill, see [Join behavior](https://github.com/fluencelabs/aqua-book/tree/4177e00f9313f0e1eb0a60015e1c19a956c065bd/language/operators/parallel.md#join-behavior).
 
 {% hint style="warning" %}
 The `!` operator can currently only be used with literal indices.  
@@ -115,11 +114,10 @@ That is,`!2` is valid but`!x` is not valid.
 We expect to address this limitation soon.
 {% endhint %}
 
-### Assignments
+## Assignments
 
 Assignments, `=`, only give a name to a value with applied getter or to a literal.
 
-
 ```text
 func foo(arg: bool, e: Example):
   -- Rename the argument
@@ -130,7 +128,7 @@ func foo(arg: bool, e: Example):
   c = "just string value"
 ```
 
-### Constants
+## Constants
 
 Constants are like assignments but in the root scope. They can be used in all function bodies, textually below the place of const definition. Constant values must resolve to a literal.
 
@@ -150,7 +148,7 @@ func bar():
   foo(setting)
 ```
 
-### Visibility scopes
+## Visibility scopes
 
 Visibility scopes follow the contracts of execution flow.
 
@@ -161,7 +159,7 @@ Functions have isolated scopes:
 ```text
 func foo():
    a = 5
-   
+
 func bar():
    -- a is not defined in this function scope
    a = 7   
@@ -176,9 +174,9 @@ func foo():
   for y <- ys:
     -- Can use what was defined above
     z <- bar(x)
-    
+
   -- z is not defined in scope  
-  z = 7  
+  z = 7
 ```
 
 [Parallel](flow/parallel.md#join-behavior) branches have [no access](https://github.com/fluencelabs/aqua/issues/90) to each other's data:
@@ -193,7 +191,7 @@ par y <- bar(x)
 baz(x, y)
 ```
 
-Recovery branches in [conditional flow](operators/conditional.md) have no access to the main branch as the main branch exports values, whereas the recovery branch does not:
+Recovery branches in [conditional flow](https://github.com/fluencelabs/aqua-book/tree/4177e00f9313f0e1eb0a60015e1c19a956c065bd/language/operators/conditional.md) have no access to the main branch as the main branch exports values, whereas the recovery branch does not:
 
 ```text
 try:
@@ -202,13 +200,12 @@ otherwise:
   -- this is not possible – will fail
   bar(x)  
   y <- baz()
-  
+
 -- y is not available below  
-willFail(y)  
-  
+willFail(y)
 ```
 
-### Streams as literals
+## Streams as literals
 
 Stream is a special data structure that allows many writes. It has [a dedicated article](crdt-streams.md).
 
@@ -225,13 +222,13 @@ par resp <- bar()
 for x <- xs:
   -- Write to a stream that's defined above
   resp <- baz()
-  
+
 try:
   resp <- baz()
 otherwise:
   on "other peer":
     resp <- baz()
-    
+
 -- Now resp can be used in place of arrays and optional values
 -- assume fn: []string -> ()
 fn(resp) 
@@ -239,7 +236,7 @@ fn(resp)
 -- Can call fn with empty stream: you can use it
 -- to construct empty values of any collection types
 nilString: *string
-fn(nilString)                      
+fn(nilString)
 ```
 
 One of the most frequently used patterns for streams is [Conditional return](flow/conditional.md#conditional-return).