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update 1.9

d8621cctinnus-napbus5 years ago

content/docs/hoon/hoon-school/generators.md+13−14

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@@ -16,9 +16,8 @@ There are three kinds of generators: naked, `%say`, and `%ask`. There also used

16### Naked Generators

18A naked generator is simply a `gate`; that is, it is an anonymous function that

19−takes a `sample` (argument) and produces a [noun](/docs/glossary/noun/). All you need to do is write a

19+takes a `sample` (argument) and produces a [noun](/docs/glossary/noun/). All you

20−`gate` and put it into a file in the `/gen` directory. Let's take a look at a

20+need to do is write a `gate` and put it into a file in the `/gen` directory of a desk on your ship. Let's take a look at a very simple one:

21−very simple one:

23```hoon

22```hoon

24|= a=*

23|= a=*

@@ -26,7 +25,8 @@ a

26```

25```

28This generator takes one argument of any noun and produces it without any

27This generator takes one argument of any noun and produces it without any

28+changes. Put this into a file named `echo.hoon` in the `/gen` directory of your

29−changes. Once you put this into a file named `echo.hoon` in the `/gen` directory, you must make your ship recognize the change by inputting `|commit %home` in the dojo. You can then run it from the dojo:

29+`%base` desk. You must make your ship recognize the change by inputting `|commit %base` in the dojo. You can then run it from the dojo:

31```

32> +echo 42

@@ -64,7 +64,7 @@ generator to see something more familiar:

64```

66Now let's create a generator with two arguments instead of one. Save the code

67−below as `add.hoon` in the `/gen` directory.

67+below as `add.hoon` in the `/gen` directory of your `%base` desk.

69```hoon

70|= [a=@ud b=@ud]

@@ -104,7 +104,7 @@ So, more formally, a `%say` generator is a `cell`. The head of that cell is the

104output data and the `mark` describing that data.

105

106Below is an example of a `%say` generator. Save it to `add.hoon` in the `/gen`

107−directory.

107+directory of your `%base` desk.

108

109```hoon

110:- %say

@@ -133,7 +133,7 @@ Recall that the rune `:-` produces a cell, with the first following expression

133as its head and the second following expression as its tail.

134

135The expression above creates a cell with `%say` as the head. The tail is

136−the `|= *` expression on the line that follows.

136+the `|= *` expression on the line that follows.

137

138```hoon

139|= *

@@ -141,10 +141,10 @@ the `|= *` expression on the line that follows.

141(add 40 2)

142```

143

144−`|= *` constructs a [gate](/docs/glossary/gate/) that takes a noun. This [gate](/docs/glossary/gate/) will itself produce a

144+`|= *` constructs a [gate](/docs/glossary/gate/) that takes a noun. This [gate](/docs/glossary/gate/) will itself produce a

145`cask`, which is cell formed by the prepending `:-`. The head of that `cask` is

146`%noun` and the tail is the rest of the program, `(add 40 2)`. The tail of the

147−`cask` will be our actual data produced by the body of the program: in this

147+`cask` will be our actual data produced by the body of the program: in this

148case, just adding 40 and 2 together.

149

150#### `%say` generators with arguments

@@ -216,7 +216,7 @@ second part, besides its position:

216```

217

218Let's look at an example that uses all three parts. Save the code below in a

219−file called `dice.hoon` in your `/gen` directory.

219+file called `dice.hoon` in the `/gen` directory of your `%base` desk.

220

221```hoon

222:- %say

@@ -311,7 +311,7 @@ to explain how this kind of generator works.

311##### `%ask` example

312

313The code below is an `%ask` generator that checks if the user inputs "blue" when

314−prompted. Save it as `axe.hoon` in `/gen`.

314+prompted. Save it as `axe.hoon` in the `/gen` directory of your `%base` desk.

315

316```hoon

317/- sole

@@ -379,7 +379,7 @@ This code might be familiar. Just as with their `%say` cousins, `%ask`

379generators need to produce a `cell`, the head of which specifies what kind of

380generator we are running.

381

382−With `|= *`, we create a gate and ignore the standard arguments we are given,

382+With `|= *`, we create a gate and ignore the standard arguments we are given,

383because we're not using them.

384

385```hoon

@@ -434,7 +434,6 @@ use to prompt the user. In the case of our example, we use `"color: "`.

434**`produce`** is used to construct the output of the generator. In our example,

435we produce a `tang`.

436

437−

438```hoon

437```hoon

439|= t=tape

438|= t=tape

440```

439```

@@ -458,4 +457,4 @@ This is a [known issue](https://github.com/urbit/arvo/issues/840) to be resolved

458

457

459## Conclusion

458## Conclusion

460

459

461−You've now reached the end of Chapter 1 of the Hoon tutorial. Ideally you should have a fair understanding of the fundamental concepts of subject-oriented programming: limbs, legs, faces, wings, arms, cores, gates, and [doors](/docs/glossary/door/). If you can master these concepts you should have little or no trouble learning to write substantial Hoon programs.

460+You've now reached the end of Chapter 1 of the Hoon tutorial. Ideally you should have a fair understanding of the fundamental concepts of subject-oriented programming: limbs, legs, faces, wings, arms, cores, gates, and [doors](/docs/glossary/door/). If you can master these concepts you should have little or no trouble learning to write substantial Hoon programs.