Class: Skeem::SkmBindingBlock

Inherits:
SkmUnaryExpression show all
Defined in:
lib/skeem/skm_unary_expression.rb

Overview

Used to represent local binding constructs (let, let*, letrec, letrec*)

Instance Attribute Summary collapse

Attributes inherited from SkmUnaryExpression

#child

Attributes inherited from SkmElement

#position

Instance Method Summary collapse

Methods inherited from SkmUnaryExpression

#accept

Methods inherited from SkmElement

#accept, #boolean?, #bound!, #callable?, #char?, #complex?, #done!, #eqv?, #inspect, #integer?, #list?, #null?, #number?, #pair?, #procedure?, #quasiquote, #quoted!, #rational?, #real?, #skm_eq?, #skm_equal?, #string?, #symbol?, #unquoted!, #vector?, #verbatim?

Constructor Details

#initialize(theKind, theBindings, aBody) ⇒ SkmBindingBlock

Returns a new instance of SkmBindingBlock.



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# File 'lib/skeem/skm_unary_expression.rb', line 123

def initialize(theKind, theBindings, aBody)
  @kind = theKind
  @bindings = theBindings
  super(nil, aBody)
end

Instance Attribute Details

#bindings ⇒ Array<SkmBinding> (readonly)

Returns:



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# File 'lib/skeem/skm_unary_expression.rb', line 121

def bindings
  @bindings
end

#kind ⇒ Symbol (readonly)

Returns One of: :let, :let_star.

Returns:

  • (Symbol) —

    One of: :let, :let_star



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# File 'lib/skeem/skm_unary_expression.rb', line 118

def kind
  @kind
end

Instance Method Details

#evaluate(aRuntime) ⇒ Object 



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# File 'lib/skeem/skm_unary_expression.rb', line 129

def evaluate(aRuntime)
  aRuntime.push(SkmFrame.new(aRuntime.environment))
  case kind
  when :let
    locals = bindings.map do |bnd|
      SkmBinding.new(bnd.variable, bnd.value.evaluate(aRuntime))
    end
    locals.each do |bnd|
      aRuntime.add_binding(bnd.variable.evaluate(aRuntime), bnd.value)
    end
  when :let_star
    bindings.each do |bnd|
      val = bnd.value.evaluate(aRuntime)
      aRuntime.add_binding(bnd.variable.evaluate(aRuntime), val)
    end
  end

  unless body[:defs].empty?
    body[:defs].each do |dfn|
      dfn.evaluate(aRuntime)
    end
  end

  # $stderr.puts "Environment SkmBindingBlock#evaluate:" + aRuntime.environment.inspect
  raw_result = body[:sequence].evaluate(aRuntime)
  result = raw_result.kind_of?(SkmPair) ? raw_result.last : raw_result
  result = result.doppelganger(aRuntime) if result.kind_of?(SkmLambda)

  aRuntime.pop
  # $stderr.puts "Result SkmBindingBlock#evaluate: " + result.inspect
  result
end