ailrk/blgol60

Algol 60 60 years later

blgol60's Issues

Use unsafePerformIO for symbol cache

The symbol lookup and temporary name generators are memoized: they will only compute the key once, then the result will be stored in a memoization table. The problem is to use what for storing these states. To avoid unsafePerformIO, I need to wrap all operations in a state monad, and the entire computation also needs to be in the state monad to remember the change. This introduces two problems: 1. there will be an extra layer of monad, and that clutter the code. 2. Memoization table only serves the purpose of speeding up lookup, the side effect isn't really observable at all. Extra work is really not necessary.

I think a global memoization table is a legit use for the global mutable state. The goal is to have something like unsafePerformIO (newIORef HM.mepty) for recording the state and insertions will be in IO monad.

Need a graph library for flow control

Write a small graph module just for this project.

Implement ASTShow

AST is stable now, so there should be a pretty printer.

Wrong precedent when parsing if expression

from Test.hs, with runAll exprTest

=== 5 ================                                                                
  "if true and false then 1 + 3 * 2 else 4 < 10"
                                           
Left "-"
    ( line 1          
    , column 3                         
    ) :
  unexpected reserved word "if" expecting simple expression
                  
=== 8 ================
  "if not b > 3 then c >= 2 else c < 4"

Left "-"
    ( line 1
    , column 3
    ) :
  unexpected reserved word "if" expecting simple expression