Module: Dhallish

Included in:
Ast
Defined in:
lib/ast.rb,
lib/types.rb,
lib/stdlib.rb,
lib/dhallish.rb

Defined Under Namespace

Modules: Ast, Types Classes: BuiltinFunction, Context, Function, Union

Constant Summary collapse

@@parser = 
DhallishGrammarParser.new

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.create_ctx(dhallcode, basedir = Dir.pwd) ⇒ Object 



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# File 'lib/dhallish.rb', line 53

def create_ctx(dhallcode, basedir=Dir.pwd)
  empty_ctx = empty_context(basedir)
  ctx, type = evaluate(dhallcode, empty_ctx)
  if type != Types::Record.new({}) or ctx["<#TYPES#>"].nil? or ctx["<#VALS#>"].nil?
    raise DhallError, "return type of dhallcode supplied to `create_ctx` did not return a context (but something of type `#{type}`). use `???`"
  end
  ctx
end

.empty_context(basedir = Dir.pwd) ⇒ Object 



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# File 'lib/dhallish.rb', line 20

def empty_context(basedir=Dir.pwd)
  ctx = { "<#TYPES#>" => Context.new, "<#VALS#>" => Context.new }
  ctx["<#TYPES#>"]["<#DIR#>"] = basedir
  fill_context(ctx["<#VALS#>"], ctx["<#TYPES#>"])
  ctx
end

.evaluate(dhallcode, ctx = nil, expected_type = nil) ⇒ Object 



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# File 'lib/dhallish.rb', line 28

def evaluate(dhallcode, ctx=nil, expected_type=nil)
  if ctx.nil?; ctx = empty_context() end

  rawast = @@parser.parse dhallcode
  if rawast.nil?
    raise DhallError, "#{@@parser.failure_reason} (line/column: #{@@parser.failure_line}:#{@@parser.failure_column})"
  end

  ast = rawast.to_node

  type = ast.compute_type ctx["<#TYPES#>"]
  res = ast.evaluate ctx["<#VALS#>"]

  if !expected_type.nil?
    if !(type == expected_type)
      raise DhallError, "expression return type missmatch: expected `#{expected_type}`, got: `#{type}`"
    else
      res
    end
  else
    [res, type]
  end
end

.fill_context(globalctx, types) ⇒ Object 



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# File 'lib/stdlib.rb', line 24

def fill_context(globalctx, types)

  # Types:
  globalctx["Natural"] = Types::Natural
  globalctx["Integer"] = Types::Integer
  globalctx["Double"] = Types::Double
  globalctx["Bool"] = Types::Bool
  globalctx["Text"] = Types::Text
  globalctx["Type"] = Types::Type.new

  types["Natural"] = Types::Type.new(Types::Natural)
  types["Integer"] = Types::Type.new(Types::Integer)
  types["Double"] = Types::Type.new(Types::Double)
  types["Bool"] = Types::Type.new(Types::Bool)
  types["Text"] = Types::Type.new(Types::Text)
  types["Type"] = Types::Type.new(Types::Type.new)

  # Shows:
  globalctx["Natural/show"] = BuiltinFunction.new { |arg| arg.to_s }
  types["Natural/show"] = Types::Function.new(Types::Natural, Types::Text)

  globalctx["Integer/show"] = BuiltinFunction.new { |arg| arg.to_s }
  types["Integer/show"] = Types::Function.new(Types::Integer, Types::Text)

  globalctx["Double/show"] =  BuiltinFunction.new { |arg| arg.to_s }
  types["Double/show"] = Types::Function.new(Types::Double, Types::Text)

  globalctx["Text/show"] = BuiltinFunction.new { |arg| arg }
  types["Text/show"] = Types::Function.new(Types::Text, Types::Text)

  # Casts:
  natToInt = BuiltinFunction.new { |arg| arg }
  globalctx["Natural/toInteger"] = natToInt
  types["Natural/toInteger"] = Types::Function.new(Types::Natural, Types::Integer)

  natToDou = BuiltinFunction.new { |arg| arg.to_f }
  globalctx["Natural/toDouble"] = natToDou
  types["Natural/toDouble"] = Types::Function.new(Types::Natural, Types::Double)


  intToNat = BuiltinFunction.new { |arg| arg.abs  }
  globalctx["Integer/toNatural"] = intToNat
  types["Integer/toNatural"] = Types::Function.new(Types::Integer, Types::Natural)

  intToDou = BuiltinFunction.new { |arg| arg.to_f }
  globalctx["Integer/toDouble"] = intToDou
  types["Integer/toDouble"] = Types::Function.new(Types::Integer, Types::Double)


  douToNat = BuiltinFunction.new { |arg| arg.round.abs }
  globalctx["Double/toNatural"] = douToNat
  types["Double/toNatural"] = Types::Function.new(Types::Double, Types::Natural)

  douToInt = BuiltinFunction.new { |arg| arg.round }
  globalctx["Double/toInteger"] = douToInt
  types["Double/toInteger"] = Types::Function.new(Types::Double, Types::Integer)


  # Lists:
  globalctx["List"] = BuiltinFunction.new { |a| Types::List.new(a) }
  types["List"] = make_fn_type([:list_a], Types::Type.new(Types::List.new(Types::Unresolved.new(:list_a))))

  list_length_type = make_fn_type([:list_len_a], Types::List.new(Types::Unresolved.new(:list_len_a)), Types::Natural)
  globalctx["List/length"] = BuiltinFunction.new{ |a|
    BuiltinFunction.new { |list|
      list.length
    }
  }
  types["List/length"] = list_length_type

  list_fold_type = make_fn_type(
    [:list_fold_a],
    Types::List.new(Types::Unresolved.new(:list_fold_a)),
    [:list_fold_b],
    make_fn_type(:list_fold_a, :list_fold_b, :list_fold_b),
    :list_fold_b, :list_fold_b)
  globalctx["List/fold"] = BuiltinFunction.new { |a|
    BuiltinFunction.new { |list|
      BuiltinFunction.new { |b|
        BuiltinFunction.new { |f|
          BuiltinFunction.new { |x|
            acc = x
            list.reverse_each { |elm| acc = f.call(elm).call(acc) }
            acc
          }
        }
      }
    }
  }
  types["List/fold"] = list_fold_type

  list_head_type = make_fn_type(
    [:list_head_a],
    Types::List.new(Types::Unresolved.new(:list_head_a)),
    Types::Optional.new(Types::Unresolved.new(:list_head_a)))
  globalctx["List/head"] = BuiltinFunction.new { |a|
    BuiltinFunction.new { |list|
      list.first
    }
  }
  types["List/head"] = list_head_type

  list_last_type = make_fn_type(
    [:list_last_a],
    Types::List.new(Types::Unresolved.new(:list_last_a)),
    Types::Optional.new(Types::Unresolved.new(:list_last_a)))
  globalctx["List/last"] = BuiltinFunction.new { |a|
    BuiltinFunction.new { |list|
      list.last
    }
  }
  types["List/last"] = list_last_type

  list_tail_type = make_fn_type(
    [:list_tail_a],
    Types::List.new(Types::Unresolved.new(:list_tail_a)),
    Types::List.new(Types::Unresolved.new(:list_tail_a)))
  globalctx["List/tail"] = BuiltinFunction.new { |a|
    BuiltinFunction.new { |list|
      if list.empty?
        []
      else
        list[1..list.length]
      end
    }
  }
  types["List/tail"] = list_tail_type

  types["List/reverse"] = make_fn_type(
    [:list_reverse_a],
    Types::List.new(Types::Unresolved.new(:list_reverse_a)),
    Types::List.new(Types::Unresolved.new(:list_reverse_a)))
  globalctx["List/reverse"] = BuiltinFunction.new { |a|
    BuiltinFunction.new { |list| list.reverse }
  }

  types["List/build"] = make_fn_type(
    [:list_build_a],
    make_fn_type(
      [:list_build_b],
      make_fn_type(:list_build_a, :list_build_b, :list_build_b), :list_build_b, :list_build_b),
    Types::List.new(Types::Unresolved.new(:list_build_a)))
  globalctx["List/build"] = BuiltinFunction.new { |a|
    BuiltinFunction.new { |f|
      cons = BuiltinFunction.new { |x|
        BuiltinFunction.new { |list| [x] + list }
      }
      f.call(Types::List.new(a)).call(cons).call([])
    }
  }

  types["List/indexed"] = make_fn_type(
    [:list_indexed_a],
    Types::List.new(Types::Unresolved.new(:list_indexed_a)),
    Types::List.new(Types::Record.new({
      "index" => Types::Natural,
      "value" => Types::Unresolved.new(:list_indexed_a)})))
  globalctx["List/indexed"] = BuiltinFunction.new { |a|
    BuiltinFunction.new { |list|
      list.map.with_index { |val, idx|
        { "index" => idx, "value" => val }
      }
    }
  }

  # Optionals:
  globalctx["Optional"] = BuiltinFunction.new { |a|
    Types::Optional.new(a)
  }
  types["Optional"] = make_fn_type([:opt_a], Types::Type.new(Types::Optional.new(Types::Unresolved.new(:opt_a))))

  optional_fold_type = make_fn_type(
    [:opt_fold_a],
    Types::Optional.new(Types::Unresolved.new(:opt_fold_a)),
    [:opt_fold_b],
    make_fn_type(:opt_fold_a, :opt_fold_b),
    :opt_fold_b, :opt_fold_b)
  globalctx["Optional/fold"] = BuiltinFunction.new { |a|
    BuiltinFunction.new { |opt|
      BuiltinFunction.new { |b|
        BuiltinFunction.new { |f|
          BuiltinFunction.new { |x|
            if opt.nil?
              x
            else
              f.call(opt)
            end
          }
        }
      }
    }
  }
  types["Optional/fold"] = optional_fold_type

  types["Optional/build"] = make_fn_type(
    [:opt_build_a],
    make_fn_type([:opt_build_b],
      make_fn_type(:opt_build_a, :opt_build_b), :opt_build_b, :opt_build_b),
    Types::Optional.new(Types::Unresolved.new(:opt_build_a)))
  globalctx["Optional/build"] = BuiltinFunction.new { |a|
    BuiltinFunction.new { |f|
      just = BuiltinFunction.new { |x| x }
      f.call(Types::Optional.new(a)).call(just).call(nil)
    }
  }


  # Naturals:
  natural_fold_type = make_fn_type(
    Types::Natural,
    [:nat_fold_a],
    make_fn_type(:nat_fold_a, :nat_fold_a),
    :nat_fold_a, :nat_fold_a)
  globalctx["Natural/fold"] = BuiltinFunction.new { |n|
    BuiltinFunction.new { |a|
      BuiltinFunction.new { |succ|
        BuiltinFunction.new { |zero|
          res = zero
          n.times { res = succ.call(res) }
          res
        }
      }
    }
  }
  types["Natural/fold"] = natural_fold_type

  types["Natural/even"] = make_fn_type(Types::Natural, Types::Bool)
  globalctx["Natural/even"] = BuiltinFunction.new { |n| n % 2 == 0 }

  types["Natural/odd"] = make_fn_type(Types::Natural, Types::Bool)
  globalctx["Natural/odd"] = BuiltinFunction.new { |n| n % 2 == 1 }

  types["Natural/isZero"] = make_fn_type(Types::Natural, Types::Bool)
  globalctx["Natural/isZero"] = BuiltinFunction.new { |n| n == 0 }

  globalctx["Natural/build"] = BuiltinFunction.new { |f|
    zero = 0
    succ = BuiltinFunction.new { |n| n + 1 }
    f.call(Types::Natural).call(succ).call(zero)
  }
  types["Natural/build"] = make_fn_type(make_fn_type([:nat_build_a], make_fn_type(:nat_build_a, :nat_build_a), :nat_build_a, :nat_build_a), Types::Natural)

end

.make_fn_type(*args, rettype) ⇒ Object

Utility function to create dhallish function types: Use [:name] to introduce a new unresolved type and write :name to use it. Look at ‘fill_context` for examples.



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# File 'lib/stdlib.rb', line 9

def make_fn_type(*args, rettype)
  if Types::not_a_type?(rettype); rettype = Types::Unresolved.new(rettype) end
  args.reverse.reduce(rettype) { |rettype, arg|
    argtype = arg
    name = nil
    if arg.is_a? Array
      name = arg[0]
      argtype = Types::Type.new(Types::Unresolved.new(name))
    end
    if Types::not_a_type?(argtype); argtype = Types::Unresolved.new(argtype) end
    Types::Function.new(argtype, rettype, name)
  }
end

.mergeRecordsPrefereRight(a, b) ⇒ Object 



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# File 'lib/types.rb', line 434

def mergeRecordsPrefereRight(a, b)
  mergedVals = a.clone
  b.each { |key, val| mergedVals[key] = val }
  mergedVals
end

.mergeRecordsRecursively(a, b) ⇒ Object

TODO: .val weg!



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# File 'lib/types.rb', line 409

def mergeRecordsRecursively(a, b)
  merged = a.clone
  b.each { |key, val|
    if merged.key? key
      if val.is_a? Hash and merged[key].is_a? Hash
        merged[key] = mergeRecordsRecursively(merged[key], val)
      else
        raise DhallError, "key `#{key}` apeares in left and right side of `/\\` (should not happen becouse of static type checks)"
      end
    else
      merged[key] = val
    end
  }
  merged
end

.mergeRecordTypes(a, b) ⇒ Object 



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# File 'lib/types.rb', line 388

def mergeRecordTypes(a, b)
  assert("records expected") { a.is_a? Types::Record and b.is_a? Types::Record }

  merged = a.types.clone
  b.types.each { |key, type|
    if merged.key? key
      if type.is_a? Types::Record and merged[key].is_a? Types::Record
        merged[key] = mergeRecordTypes(merged[key], type)
      else
        raise DhallError, "key `#{key}` apeares in left and right side of `//\\\\` with different types"
      end
    else
      merged[key] = type
    end
  }

  Types::Record.new merged
end

.mergeRecordTypesPrefereRight(a, b) ⇒ Object 



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# File 'lib/types.rb', line 426

def mergeRecordTypesPrefereRight(a, b)
  assert("expecting records for `//`") { a.is_a? Types::Record and b.is_a? Types::Record }
  mergedTypes = a.types.clone
  b.types.each { |key, type| mergedTypes[key] = type }
  Types::Record.new(mergedTypes)
end

.to_json(dhallval) ⇒ Object 



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# File 'lib/types.rb', line 292

def to_json(dhallval)
  case dhallval
  when Integer
    dhallval.to_s
  when Float
    dhallval.to_s
  when String
     "\"#{escape_str(dhallval)}\""
  when TrueClass
    "true"
  when FalseClass
    "false"
  when Array
    "[#{ dhallval.map{ |val| to_json(val) }.join(", ") }]"
  when Hash
    "{#{ dhallval.map{ |key, val| "\"#{escape_str(key)}\": #{ to_json(val) }" }.join(", ") }}"
  when nil
    "null"
  else
    if Types::is_a_type? dhallval
      "\"#{dhallval.to_s}\""
    else
      "\"<#{escape_str(dhallval.class.to_s)}##{dhallval.hash.abs.to_s(16)}>\""
    end
  end
end

Instance Method Details

#create_ctx_from_file(dhallfile, basedir = nil) ⇒ Object 



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# File 'lib/dhallish.rb', line 63

def create_ctx_from_file(dhallfile, basedir=nil)
  if basedir.nil?; basedir = File.dirname(dhallfile) end
  file = File.open(dhallfile)
  res = create_ctx(file.read, basedir)
  file.close
  res
end