doc/ref: remove ranges from spec
With the addition of unary operators, ranges are superfluous.
Advantages:
- less things to learn
- removes a level of operator precedence
- removes an operator
- removes somewhat complicated semantics
for ranges of two different types
Change-Id: Ia705bf578ef5a5d2a49620b2cfc5190c881d1b06
diff --git a/doc/ref/spec.md b/doc/ref/spec.md
index 34049aa..0b56d40 100644
--- a/doc/ref/spec.md
+++ b/doc/ref/spec.md
@@ -273,7 +273,7 @@
- mod || < <= [ ]
* quo ! > >= { }
/ rem & : <- ; ,
-% _|_ | = ... .. .
+% _|_ | = ... .
```
<!-- :: for "is-a" definitions -->
@@ -857,7 +857,7 @@
### Bounds
A _bound_, syntactically_ a [unary expression](#Operands), defines
-a (possibly infinite) disjunction of concrete values than can be represented
+an infinite disjunction of concrete values than can be represented
as a single comparison.
For any [comparison operator](#Comparison-operators) `op` except `==`,
@@ -867,7 +867,7 @@
2 & >=2 & <=5 // 2, where 2 is either an int or float.
2.5 & >=1 & <=5 // 2.5
2 & >=1.0 & <3.0 // 2.0
-2 & 1..3.0 // 2.0
+2 & >1 & <3.0 // 2.0
2.5 & int & >1 & <5 // _|_
2.5 & float & >1 & <5 // 2.5
int & 2 & >1.0 & <3.0 // _|_
@@ -878,32 +878,6 @@
```
-### Ranges
-
-A _range type_, syntactically a [binary expression](#Operands), defines
-a (possibly infinite) disjunction of concrete values that can be represented
-as a contiguous range.
-A concrete value `c` unifies with `a..b` if `a <= c` and `c <= b`.
-Ranges can be defined on numbers and strings.
-
-A range of numbers `a..b` defines an inclusive range for integers and
-floating-point numbers.
-
-Remember that an integer literal represents both an `int` and `float`:
-```
-2 & 1..5 // 2, where 2 is either an int or float.
-2.5 & 1..5 // 2.5
-2 & 1.0..3.0 // 2.0
-2 & 1..3.0 // 2.0
-2.5 & int & 1..5 // _|_
-2.5 & float & 1..5 // 2.5
-int & 2 & 1.0..3.0 // _|_
-2.5 & (int & 1)..5 // _|_
-0..7 & 3..10 // 3..7
-"foo" & "a".."n" // "foo"
-```
-
-
### Structs
A _struct_ is a set of elements called _fields_, each of
@@ -965,20 +939,21 @@
```
```
-Expression Result
-{a: int, a: 1} {a: int(1)}
-{a: int} & {a: 1} {a: int(1)}
-{a: 1..7} & {a: 5..9} {a: 5..7}
-{a: 1..7, a: 5..9} {a: 5..7}
+Expression Result
+{a: int, a: 1} {a: int(1)}
+{a: int} & {a: 1} {a: int(1)}
+{a: >=1 & <=7} & {a: >=5 & <=9} {a: >=5 & <=7}
+{a: >=1 & <=7, a: >=5 & <=9} {a: >=5 & <=7}
-{a: 1} & {b: 2} {a: 1, b: 2}
-{a: 1, b: int} & {b: 2} {a: 1, b: int(2)}
+{a: 1} & {b: 2} {a: 1, b: 2}
+{a: 1, b: int} & {b: 2} {a: 1, b: int(2)}
-{a: 1} & {a: 2} _|_
+{a: 1} & {a: 2} _|_
```
In addition to fields, a struct literal may also define aliases.
-Aliases name values that can be referred to within the [scope](#declarations-and-scopes) of their
+Aliases name values that can be referred to
+within the [scope](#declarations-and-scopes) of their
definition, but are not part of the struct: aliases are irrelevant to
the partial ordering of values and are not emitted as part of any
generated data.
@@ -1136,19 +1111,19 @@
Derived Value
number int | float
-uint 0..int
-uint8 0..255
-int8 -128..127
-uint16 0..65536
-int16 -32_768...32_767
-rune 0..0x10FFFF
-uint32 0..4_294_967_296
-int32 -2_147_483_648..2_147_483_647
-uint64 0..18_446_744_073_709_551_615
-int64 -9_223_372_036_854_775_808..9_223_372_036_854_775_807
-uint128 340_282_366_920_938_463_463_374_607_431_768_211_455
-int128 -170_141_183_460_469_231_731_687_303_715_884_105_728..
- 170_141_183_460_469_231_731_687_303_715_884_105_727
+uint >=0
+uint8 >=0 & <=255
+int8 >=-128 & <=127
+uint16 >=0 & <=65536
+int16 >=-32_768 & <=32_767
+rune >=0 & <=0x10FFFF
+uint32 >=0 & <=4_294_967_296
+int32 >=-2_147_483_648 & <=2_147_483_647
+uint64 >=0 & <=18_446_744_073_709_551_615
+int64 >=-9_223_372_036_854_775_808 & <=9_223_372_036_854_775_807
+uint128 >=0 & <=340_282_366_920_938_463_463_374_607_431_768_211_455
+int128 >=-170_141_183_460_469_231_731_687_303_715_884_105_728 &
+ <=170_141_183_460_469_231_731_687_303_715_884_105_727
```
@@ -1412,7 +1387,7 @@
Expression = UnaryExpr | Expression binary_op Expression .
UnaryExpr = PrimaryExpr | unary_op UnaryExpr .
-binary_op = "|" | "&" | "||" | "&&" | "==" | rel_op | add_op | mul_op | ".." .
+binary_op = "|" | "&" | "||" | "&&" | "==" | rel_op | add_op | mul_op .
rel_op = "!=" | "<" | "<=" | ">" | ">=" .
add_op = "+" | "-" .
mul_op = "*" | "/" | "%" | "div" | "mod" | "quo" | "rem" .
@@ -1436,14 +1411,13 @@
Unary operators have the highest precedence.
There are eight precedence levels for binary operators.
-The `..` operator (range) binds strongest, followed by
-multiplication operators, addition operators, comparison operators,
+Multiplication operators binds strongest, followed by
+addition operators, comparison operators,
`&&` (logical AND), `||` (logical OR), `&` (unification),
and finally `|` (disjunction):
```
Precedence Operator
- 8 ..
7 * / % div mod quo rem
6 + -
5 == != < <= > >=
@@ -1579,8 +1553,8 @@
Suggestion from jba:
Multiplication should distribute over disjunction,
so int(1)..int(3) * [x] = [x] | [x, x] | [x, x, x].
-The hard part is figuring out what 1..3 * [x] means,
-since 1..3 includes many floats.
+The hard part is figuring out what (>=1 & <=3) * [x] means,
+since >=1 & <=3 includes many floats.
(mpvl: could constrain arguments to parameter types, but needs to be
done consistently.)
-->
@@ -1641,11 +1615,11 @@
<!-- jba
I think I know what `3 < a` should mean if
- a: 1..5
-
+ a: >=1 & <=5
+
It should be a constraint on `a` that can be evaluated once `a`'s value is known more precisely.
-But what does `3 < 1..5` mean? We'll never get more information, so it must have a definite value.
+But what does `3 < (>=1 & <=5)` mean? We'll never get more information, so it must have a definite value.
-->
#### Logical operators
