[PATCH olang v2 0/2] docs: variables specification

[PATCH olang v2 0/2] docs: variables specification

[Carlos Maniero]

This patchset specifies variables and constants.

Main changes in v2:
- Simplifications suggested by Johnny related to EOF
- Support all assign operators

There are two things a left outside this patchset:

1. The statement *const a += 2* is still valid at this spec.

I tried to fix it but it ends up too much complex. I'm not sure we need
to be so strict on the spec. The C spec does the same so I think  we are
fine.

2. Chained assignment

The statement *a = b = c* is not valid right now. We could discuss if
this is something that we really want to incorporate in the language.
The main reason are:

- It is hard to implement and it may mess with the great expression
  precedence algorithm we have right now.
- It brings complexity for the spec, the version we had at the previous
  discussion the statement *return = 2* was valid.

Fun fact that does not need to be considered:

- In gcc *a = b = 2* is slower then *a = 2*, *b = 2* once it actually
  makes *a = 2; b = a* requiring an extra instruction to copy the value
  from *a* at the stack to a register. But it is probably solved by
  enabling *-O3*

Do you think we can deal with chained assignment latter?

Carlos Maniero (2):
  docs: spec: rename program to translation-unit
  docs: spec: add variables and constants specification

 docs/pages/language-specification.md | 32 ++++++++++++++++++++++------
 1 file changed, 25 insertions(+), 7 deletions(-)

-- 
2.34.1

[PATCH olang v2 1/2] docs: spec: rename program to translation-unit

[Carlos Maniero]

Signed-off-by: Carlos Maniero <carlos@maniero.me>
---
 docs/pages/language-specification.md | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/docs/pages/language-specification.md b/docs/pages/language-specification.md
index 5769d95..544741a 100644
--- a/docs/pages/language-specification.md
+++ b/docs/pages/language-specification.md
@@ -22,8 +22,7 @@ language.
 
 ```
 (* Entry Point *)
-<program>             ::= <ows> <function-definition> <ows> <end-of-file>
-
+<translation-unit>    ::= <ows> <function-definition> <ows> <end-of-file>
 (* Functions *)
 <function-definition> ::= 'fn' <ws> <function-name> <ows>
 <function-parameters> <ows> ':' <ows> <return-type> <ows> <function-body>
-- 
2.34.1

[PATCH olang v2 2/2] docs: spec: add variables and constants specification

[Carlos Maniero]

This commit introduces the specification for variables and constants. A
valid program under this specification is as follows:

  var x: u32 = 1
  const y: u32 = 2

  fn main(): u32 {
    var x: u32 = 1; const y: u32 = 2
    return x
  }

Signed-off-by: Carlos Maniero <carlos@maniero.me>
---
 docs/pages/language-specification.md | 33 ++++++++++++++++++++++------
 1 file changed, 26 insertions(+), 7 deletions(-)

diff --git a/docs/pages/language-specification.md b/docs/pages/language-specification.md
index 544741a..4d0eb36 100644
--- a/docs/pages/language-specification.md
+++ b/docs/pages/language-specification.md
@@ -22,24 +22,43 @@ language.
 
 ```
 (* Entry Point *)
-<translation-unit>    ::= <ows> <function-definition> <ows> <end-of-file>
+<translation-unit>     ::= (<ows> <external-declaration> <ows> (<end-of-statement> | <end-of-file>))*
+
+<external-declaration> ::= <function-definition> | <variable-definition>
+
+(* Variables *)
+<variable-definition>  ::= <variable-qualifier> <ws> <variable-name> <ows> ':' <ows> <type> (<ows> <assign-operator> <ows> <expression>)?
+<variable-qualifier>   ::= 'var'
+                         | 'const'
+<variable-name>        ::= <identifier>
+
 (* Functions *)
-<function-definition> ::= 'fn' <ws> <function-name> <ows>
-<function-parameters> <ows> ':' <ows> <return-type> <ows> <function-body>
+<function-definition> ::= 'fn' <ws> <function-name> <ows> <function-parameters> <ows> ':' <ows> <return-type> <ows> <function-body>
 <function-name>       ::= <identifier>
 <function-parameters> ::= '(' <ows> ')'
 <return-type>         ::= <type>
 <function-body>       ::= <block>
 
 (* Statements *)
-<block>               ::= '{' <ows> <statement> <ows> (<end-of-statement>
-<ows> <statement> <ows>)* <end-of-statement>? <ows> '}'
+<block>               ::= '{' <ows> <statement> <ows> (<end-of-statement> <ows> <statement> <ows>)* <end-of-statement>? <ows> '}'
 <end-of-statement>    ::= ';' | <line-break>
-<statement>           ::= <return-statement>
+<statement>           ::= <return-statement> | <variable-definition> | <assign-expression>
 <return-statement>    ::= 'return' <ws> <expression>
 
 (* Expressions *)
-<expression>          ::= <integer>
+<expression>          ::= <integer> | <identifier>
+<assign-expression>   ::= <variable-name> <ows> <assign-operator> <ows> <expression>
+<assign-operator>     ::= '='
+                        | '*='
+                        | '/='
+                        | '%='
+                        | '+='
+                        | '-='
+                        | '<<='
+                        | '>>='
+                        | '&='
+                        | '^='
+                        | '|='
 
 (* Identifiers *)
 <type>                ::= 'u32'
-- 
2.34.1

[olang/patches/.build.yml] build success

[builds.sr.ht]

olang/patches/.build.yml: SUCCESS in 39s

[docs: variables specification][0] v2 from [Carlos Maniero][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/50820
[1]: mailto:carlos@maniero.me

✓ #1189894 SUCCESS olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1189894

Re: [PATCH olang v2 0/2] docs: variables specification

[Carlos Maniero]

I forgot to mention, but V1 was also allowing assignments on
external-declaration. ex:

  var x: u32
  x = 1

  fn main(): u32 {
    return x
  }

But, external-declarations should not allow statements, only
declarations/definitions.

Re: [PATCH olang v2 0/2] docs: variables specification

[Johnny Richard]

Thanks, applied!

To git.sr.ht:~johnnyrichard/olang
   099eec6..7cd840e  main -> main

build: https://builds.sr.ht/~johnnyrichard/job/1191820