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