diff options
Diffstat (limited to 'development.md')
| -rw-r--r-- | development.md | 34 |
1 files changed, 31 insertions, 3 deletions
diff --git a/development.md b/development.md index e3ec8c4..9f0980c 100644 --- a/development.md +++ b/development.md @@ -26,7 +26,7 @@ Sometimes a type ending in Ptr is defined, e.g. typedef Declaration \*Declaratio for the arr\_foreach macro, and not meant for normal use. The fixed-width types U8/16/32/64 and I8/16/32/64 have been defined. -data\_structures.c contains a dynamic array implementation which is very useful. +data\_structures.c contains a dynamic array implementation and string hash table which are very useful. ### Notes @@ -37,9 +37,9 @@ declaration). It is assumed that the number of identifiers in a declaration, or parameters to a function will fit in an int, since a function with (at least) 32768 parameters is ridiculous. +### Miscellaneous thoughts -#### Miscellaneous thoughts - +#### includes during parsing Wouldn't it be nice if `#include` could be done during typing, so that the filename wouldn't have to be a string literal? Well, unfortunately we end up in situations like this: ``` @@ -57,3 +57,31 @@ The way we evaluate `bar()` is by typing the function `bar` when we come across In order to evaluate `foo`, we need to know what it refers to, and we don't know at this point that it comes from the include, because we haven't expanded it yet. We could potentially expand all includes preceding any function which is evaluated during typing, but that seems a bit cumbersome and would probably cause other problems. + + +#### Why `#if` is complicated +Allowing arbitrary `#if` conditions leads to the following problem: +``` +bar1 ::= fn() bool { ... }; +bar2 ::= fn() bool { ... }; +foo1 ::= fn() bool { ... }; +foo2 ::= fn() bool { ... }; + +#if foo() { + bar ::= bar1; +} else { + bar ::= bar2; +} + +#if bar() { + foo ::= foo1; +} else { + foo ::= foo2; +} +``` + +In order to determine which version of `bar` to use, we need to call `foo`, and in order to determine which version of `foo` +to use, we need to call `bar`. You could just error on circular dependencies like these, but there is still the fact that you +have to figure out where the declaration for `foo` is when `foo()` is evaluated, and it could be in some other `#if`. To +avoid things getting complicated, we restrict `#if`s to make this situation impossible. While it's not ideal, it is necessary +to avoid some edge cases where we can't find out which declaration you're referring to. |