fc1a9ce · urbit.org · git.iko.soy

git.iko.soy/urbit.org

revisions to wut runes

commitfc1a9ce26bc49d069a4ae644afa506c757c4ce19 authorjoshuareagan <joshuareagan@gmail.com> dateWed 10 Oct 2018, 14:00 (8 years ago) parentaddb6f6

12 files changed+71−44

compare with master

unifiedsplit

docs/reference/rune/wut/ban.udon+18−4 docs/reference/rune/wut/col.udon+5−10 docs/reference/rune/wut/dot.udon+3−2 docs/reference/rune/wut/hep.udon+8−7 docs/reference/rune/wut/ket.udon+1−1 docs/reference/rune/wut/led.udon+16−2 docs/reference/rune/wut/lus.udon+6−4 docs/reference/rune/wut/pad.udon+1−1 docs/reference/rune/wut/sig.udon+2−4 docs/reference/rune/wut/tis.udon+5−6 docs/reference/rune/wut/vat.udon+5−2 docs/reference/rune/wut/zap.udon+1−1

docs/reference/rune/wut/ban.udon+18−4

@@ -5,9 +5,9 @@

55 ==

66;>

8−# `?> "wutgar"`

8+# `?> "wutban"`

10−`[%wtgr p=hoon q=hoon]`: positive assertion.

10+`[%wtbn p=hoon q=hoon]`: positive assertion.

1111

1212## Expands to

1313

@@ -19,12 +19,26 @@

1919

2020Regular: *2-fixed*.

2121

22+## Discussion

23+

24+`?>` is used to force a crash when some condition `p` doesn't yield 'yes', `%.y`.

25+

26+It can be used for type inference, with the `?=` rune, to specify the type of a value.

27+

2228## Examples

2329

2430```

25−~zod:dojo> ?>(=(3 3) %foo)

31+> ?>(=(3 3) %foo)

2632%foo

2733

28−~zod:dojo> ?>(=(3 4) %foo)

34+> ?>(=(3 4) %foo)

2935ford: build failed

36+

37+> =a `*`123

38+

39+> `@`a

40+nest-fail

41+

42+> ?>(?=(@ a) `@`a)

43+123

3044```

docs/reference/rune/wut/col.udon+5−10

@@ -14,16 +14,11 @@

1414If `p` produces yes, `%.y`, then `q`. If `p` produces no, `%.n`, then `r`.

1515If `p` is not a boolean, compiler yells at you.

1616

17−The subjects of `q` and `r` are constrained to match any

18−pattern-matching algebra in `p`. The analysis, which is

19−conservative, understands any combination of [`?=` ("wuttis")](../tis/),

20−[`?&` ("wutpad")](../pad/), [`?|` ("wutbar")](../bar/), and

21−[`?!` ("wutzap")](../zap/), and reduces the subject appropriately when

22−compiling.

17+### Type inference

2318

24−If test analysis reveals that either branch is not taken,

25−or if `p` is not a boolean, compilation fails. However,

26−an untaken branch can be indicated with the `%lost` hoon.

19+The subject types of `q` and `r` are constrained to match any pattern-matching algebra in `p`. The analysis, which is conservative, understands any combination of [`?=`](../tis/), [`?&`](../pad/), [`?|`](../bar/), and [`?!`](../zap/), and infers the type of the subject appropriately when compiling.

20+

21+If test analysis reveals that either branch is never taken, or if `p` is not a boolean, compilation fails. An untaken branch is indicated with `mint-lost`.

2722

2823## Syntax

2924

@@ -36,7 +31,7 @@ and includes the expected inference. For instance,

3631if you write `?&(a b)`, `b` is only executed if `a` is

3732positive, and compiled with that assumption.

3833

39−Note also that all other branching hoons reduce to `?:`.

34+Note also that all other branching expressions reduce to `?:`.

4035

4136## Examples

4237

docs/reference/rune/wut/dot.udon+3−2

@@ -21,8 +21,9 @@ Regular: *3-fixed*.

2121

2222## Discussion

2323

24−As usual with inverted forms, use `?.` ("wutdot") when the yes-case

25−expression is much taller and/or wider than the no-case expression.

24+`?.` is just like `?:`, but with its last two subexpressions reversed.

25+

26+As is usual with inverted forms, use `?.` when the yes-case expression is much taller and/or wider than the no-case expression.

2627

2728## Examples

2829

docs/reference/rune/wut/hep.udon+8−7

@@ -7,8 +7,7 @@

88# `?- "wuthep"`

10−`[%wthp p=wing q=(list (pair model value))]`: switch against a

11−union, with no default.

10+`[%wthp p=wing q=(list (pair spec value))]`: switch against a union, with no default.

1211

1312## Expands to

1413

@@ -39,10 +38,12 @@ Regular: *1-fixed*, then *jogging*.

3938

4039## Discussion

4140

41+The `?-` rune is for a conditional expression in which the type of `p` determines which branch is taken. Usually the type of `p` is a union of other types. There is no default branch.

42+

4243The compiler makes sure that your code neither misses a case of

4344the union, nor includes a double case that isn't there. This is

44−not special handling for `?-` ("wuthep"), just a consequence of the

45−semantics of `?:` ("wutcol"), which `?-` reduces to.

45+not special handling for `?-`, just a consequence of the

46+semantics of `?:`, which `?-` reduces to.

4647

4748A missing case will throw the `mint-lost` error. An extra case

4849will throw `mint-vain`.

@@ -50,10 +51,10 @@ will throw `mint-vain`.

5051## Examples

5152

5253```

53−~zod:dojo> =cor |= vat=?($a $b)

54+~zod:dojo> =cor |= vat=?(%a %b)

5455 ?- vat

55− $a 20

56− $b 42

56+ %a 20

57+ %b 42

5758 ==

5859

5960~zod:dojo> (cor %a)

docs/reference/rune/wut/ket.udon+1−1

@@ -22,7 +22,7 @@ Regular: *3-fixed*.

2222

2323## Discussion

2424

25−Regular form: *3-fixed*

25+The type of the wing, `p`, must not be known to be either an atom or a cell, or else you'll get a `mint-vain` error at compile time. `mint-vain` means that one of the `?^` branches, `q` or `r`, is never taken.

2626

2727## Examples

2828

docs/reference/rune/wut/led.udon+16−2

@@ -19,12 +19,26 @@

1919

2020Regular: *2-fixed*.

2121

22+## Discussion

23+

24+`?<` is used to force a crash when some condition `p` doesn't yield 'no', `%.n`.

25+

26+It can be used for type inference with the `?=` rune, much like the `?>` rune.

27+

2228## Examples

2329

2430```

25−~zod:dojo> ?<(=(3 4) %foo)

31+> ?<(=(3 4) %foo)

2632%foo

2733

28−~zod:dojo> ?<(=(3 3) %foo)

34+> ?<(=(3 3) %foo)

2935ford: build failed

36+

37+> =a `*`[12 14]

38+

39+> `^`a

40+nest-fail

41+

42+> ?<(?=(@ a) `^`a)

43+[12 14]

3044```

docs/reference/rune/wut/lus.udon+6−4

@@ -39,15 +39,17 @@ Regular: *2-fixed*, then *jogging*.

3939

4040## Discussion

4141

42−An extra case will throw `mint-vain`. A lost case defaults.

42+The `?+` rune is for a conditional expression in which the type of `p` determines which branch is taken. Usually the type of `p` is a union of other types. If `p`'s type doesn't match the case for any given branch, the default expression, `q`, is evaluated.

43+

44+If there is a case that is never taken you'll get a `mint-vain` error.

4345

4446## Examples

4547

4648```

47−~zod:dojo> =cor |= vat=?($a $b)

49+~zod:dojo> =cor |= vat=?(%a %b)

4850 ?+ vat 240

49− $a 20

50− $b 42

51+ %a 20

52+ %b 42

5153 ==

5254

5355~zod:dojo> (cor %a)

docs/reference/rune/wut/pad.udon+1−1

@@ -7,7 +7,7 @@

88# `?& "wutpad"`

10−`[%wtpm p=(list hoon)]`: logical AND.

10+`[%wtpd p=(list hoon)]`: logical AND.

1111

1212## Expands to

1313

docs/reference/rune/wut/sig.udon+2−4

@@ -7,8 +7,7 @@

88# `?~ "wutsig"`

10−`[%wtsg p=wing q=hoon r=hoon]`: branch on whether a wing

11−of the subject is null.

10+`[%wtsg p=wing q=hoon r=hoon]`: branch on whether a wing of the subject is null.

1211

1312## Expands to

1413

@@ -22,8 +21,7 @@ Regular: *3-fixed*.

2221

2322## Discussion

2423

25−It's bad style to use `?~` to test for any zero atom. Use it

26−only for a true null, `~`.

24+It's bad style to use `?~` to test for any zero atom. Use it only for a true null, `~`.

2725

2826## Examples

2927

docs/reference/rune/wut/tis.udon+5−6

@@ -11,8 +11,7 @@

1111

1212## Produces

1313

14−`%.y` (yes) if the noun at `q` is in the type of `p`;

15−`%.n` (no) otherwise.

14+`%.y` (yes) if the noun at `q` is in the type of `p`; `%.n` (no) otherwise.

1615

1716## Syntax

1817

@@ -20,7 +19,7 @@ Regular: *2-fixed*.

2019

2120## Discussion

2221

23−`?=` ("wuttis") is not as powerful as it might seem. For instance, it

22+`?=` is not as powerful as it might seem. For instance, it

2423can't generate a loop -- you cannot (and should not) use it to

2524test whether a `*` is a `(list @)`. Nor can it validate atomic

2625auras.

@@ -28,11 +27,11 @@ auras.

2827Patterns should be as weak as possible. Unpack one layer of

2928union at a time. Don't confirm things the type system knows.

3029

31−For example, when matching a book containing a page `[%foo p=@

32−q=[@ @]]`, the proper pattern is `[%foo *]`. You have one

30+For example, when matching from a tagged union for the type `[%foo p=@

31+q=[@ @]]`, the appropriate pattern is `[%foo *]`. You have one

3332question, which is whether the head of the noun is `%foo`.

3433

35−A common error is `find.$`, meainng `p` is not a type.

34+A common error is `find.$`, meaning `p` is not a type.

3635

3736## Examples

3837

docs/reference/rune/wut/vat.udon+5−2

@@ -7,8 +7,7 @@

88# `?@ "wutvat"`

10−`[%wtpt p=wing q=hoon r=hoon]`: branch on whether a wing

11−of the subject is an atom.

10+`[%wtpt p=wing q=hoon r=hoon]`: branch on whether a wing of the subject is an atom.

1211

1312## Expands to

1413

@@ -20,6 +19,10 @@ of the subject is an atom.

2019

2120Regular: *3-fixed*.

2221

22+## Discussion

23+

24+The type of the wing, `p`, must not be known to be either an atom or a cell, or else you'll get a `mint-vain` error at compile time. `mint-vain` means that one of the `?@` branches, `q` or `r`, is never taken.

25+

2326## Examples

2427

2528```

docs/reference/rune/wut/zap.udon+1−1

@@ -15,7 +15,7 @@

1515.=(| p)

1616```

1717

18−Produces the logical "not" of `p`.

18+Produces the logical NOT of `p`.

1919

2020## Syntax

2121