majjoha / sloth

A lazy, functional programming language.

Moof!

sloth's Issues

Implementing mark 5 features in G-machine

The features described for the mark 5 G-machine in "Implementing Functional Languages: a tutorial" needs to be implemented. This means implementing an E compilation scheme which exploits the knowledge that a particular expression will be needed in WHNF to optimize the compiled bytecode.

As an aside, we also need to implement logical AND and OR.

Finish the implementation of Mark-and-Sweep Garbage Collection for the G-machine

Note: Changes related to this issue is located on the "gc_mark2" branch.

Sub-issues

• Avoiding the accumulation of orphans. This can be a result of application nodes being converted into indirection nodes of size 1. This can be remedied by making indirection nodes of size 2. However, this also requires us to make integer nodes of size 2, thus wasting more space on the heap.
• Avoiding that the garbage collector ends up in an infinite loop where there will never be freed enough space to finish the computation. This might be connected with the fact that the heap gets segmented. Then we need functionality to reorganize the heap to free larger blocks.

Avoid reducing expressions in WHNF more than once

Currently, in the case where we have an expression which is already in WHNF, we attempt to reduce it more than once. By using a tag to indicate whether it has already been reduced to WHNF, we could avoid this.

Introduce base value stack

We never had the time to introduce a base value stack before handing in the thesis. This may prevent optimizations of environment representations as well as complicate garbage collection, since we mix base values, and pointers in the stack.