TODO 
   when calculating writeenables, use assignment
   when calculating read enables, scan list
   change parser to use <> syntax (and update all tests)

   Figure out how widths propogate for all updated primops (Adam)
   Remove letrec. Add to expressions: Register(input,en), ReadPort(mem,index,enable), WritePort(mem,index,enable) (Patrick)
   Add bit-reduce-and etc to primops (Jonathan)
   Write pass to rename identifiers (alpha-transform) (Adam)
   Add partial bulk connect (Scott, Stephen)
   Add FIFOs to the IR (Palmer)
   Registers/Memories only have data and enable fields, which can be written/read from. These are set by the front-end. This will probably have to wait (Palmer)
   Multi-streams for print statements (Jack)
   Consider def female node. (Patrick) 
   Think about supporting memories (Scott)

   Update spec
      add new field for sequential or combinational
      add assertions
   Future questions to address in spec:
      Introduction – motivation, and intended usage
      Philosophical justifications for all constructs
      More introduction for types, e.g. what is a ground type?
      What is a statement? What is an expression? What is a memory? Difference between vector type and memory? What are accessors for?
      Why would I ever write an empty statement? Mainly for use by compiler/passes
      What is a structural element? Duplication?
      Subtracting two unsigned numbers… Should talk to a math guy to figure it out
      What are shift left and shift right operations? HW doesn’t have these concepts. Need justification.
      What is lowered form? What is it for?


Checks:
   Subfields are only on bundles, before type inference 
   after adding dynamic assertions, insert bounds check with accessor expansion

Tests:
   Error if declare anything other than module in circuit
   Error if incorrectly assign stuff, like use = instead of :=
   Error: Node not parsed for stmts

Male node:
defnode n = e
==>
wire n
n := e

Female node:
defnode n = e
==>
wire n 
e := n