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86dfcefsyzygyzer7 years ago

learn/hoon/hoon-tutorial/molds.md+7−9

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unifiedsplit

@@ -4,17 +4,17 @@ weight = 0

4template = "doc.html"

5+++

7−A mold is

7+A mold is a

8+[//]: # (You should finish this thought :P)

9−Let's take some examples from `hoon.hoon`. `|$` is a new rune as of the writing of this document so you may see this spelled in slightly different way if you don't have the latest version of `hoon.hoon`.

10+Let's take some examples from `hoon.hoon`. `|$` is a new rune as of the writing of this document so you may see this spelled in slightly different way if you don't have the latest version of `hoon.hoon`. `|$` is the mold builder rune which takes a list of molds and produces a mold.

11```

12```

12++ pair

13++ pair

13 |$ [head tail]

14 |$ [head tail]

14 [p=head q=tail]

15 [p=head q=tail]

15```

16```

16−

17−Here is a very simple mold builder. It takes two molds and produces a mold that is a pair of those with the faces `p` and `q`. `|$` is the mold builder rune which takes a list of molds and produces a mold. An example of using this would be `(pair @ud @ud)` which would produce a mold for a cell of `@ud` and `@ud`.

17+Here is a very simple mold builder. It takes two molds and produces a mold that is a pair of those with the faces `p` and `q`. An example of using this would be `(pair @ud @ud)` which would produce a mold for a cell of `@ud` and `@ud`.

19```

20++ each

@@ -24,14 +24,13 @@ Here is a very simple mold builder. It takes two molds and produces a mold that

24 ==

25```

27−`each` is very slightly more complicated than `pair` was but not by much. `$%` is a rune that is a tagged union. The mold produced by this will match either `this` or `that`. An example of this would be `(each @ud @tas)` which will match either an `@ud` or a `@tas`.

27+`++each` is very slightly more complicated than `pair`. `$%` is a rune that is a tagged union. The mold produced by this will match either `this` or `that`. An example of this would be `(each @ud @tas)` which will match either an `@ud` or a `@tas`.

29```

30++ list

31 |$ [item]

32 $@(~ [i=item t=(list item)])

33```

34−

35Here is a mold builder you've used previously. `$@` is a rune that will match the first thing if it's sample is an atom and the second if the sample is a cell. You should be familiar at this point that a `list` is either `~` or a pair of an item and a list of item.

34Here is a mold builder you've used previously. `$@` is a rune that will match the first thing if it's sample is an atom and the second if the sample is a cell. You should be familiar at this point that a `list` is either `~` or a pair of an item and a list of item.

@@ -40,8 +39,7 @@ Here is a mold builder you've used previously. `$@` is a rune that will match th

40 |$ [item]

39 |$ [item]

41 [i/item t/(list item)]

40 [i/item t/(list item)]

42```

41```

43−

44−`lest` you may have heard of as a "non empty list." You can see that it lacks the `~` case that `list` has but it matches the second part of the `list` definition. Remember that Hoon types are defined by shape. `list` could also have been defined in terms of `lest` like this

42+`lest` you may have heard of as a "non empty list." You can see that it lacks the `~` case that `list` has but it matches the second part of the `list` definition. Remember that Hoon types are defined by shape. `list` could also have been defined in terms of `lest` like this:

46```

44```

47++ list

45++ list

@@ -57,4 +55,4 @@ Another possible way to write it could have been

57 $@(~ [i=item t=$])

55 $@(~ [i=item t=$])

58```

56```

60−Any of these would be equivalent.

58+Any of these would be equivalent.