I have a refugee document issued by France. Can I travel to Ireland with this, or do I need a visa?
As France is not among the countries noted, per The Republic of Ireland Naturalisation and Immigration Service (updated on 20 Jan 2017), you require a visa (emphasis mine):
Ireland accepts Convention travel documents issued by the countries listed below only.
Belgium, Czech Republic, Denmark, Finland, Germany, Hungary, Iceland, Italy, Liechtenstein, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovak Republic, Spain, Sweden, Switzerland.
If you possess a Convention travel document issued by another country, you will require a visa.