Causative constructions

When one does not carry out an action oneself but rather has the action done by someone else, this is expressed by a causative construction.

> In English it is the verb "to have" that introduces the causative: "to have" (conjuguated) + direct objet (noun or pronoun) + main verb (in its past participle form):
We'll have a monument erected on this site. I had my hair cut.

> When one wishes to designate the agent of the action (the person who has carried out the described action), there are two possibilities:
1. -- "to have" (conjuguated) + direct objet (noun or pronoun) + main verb (in its past participle form) + "by" + agent (usually not as a pronoun):
The professor had the work done by his lab assistants. I had it done by my employees.

2. -- "to have" (conjuguated) + agent (as a direct object noun or pronoun) + main verb (in its infinitive form) + the object (also in the form of a direct object noun or pronoun)
The professor had his students write an essay. I had him do it.

Note: Especially in spoken English, the verb "to get" often replaces "to have," in which case "to" is added to the infinitive (but not before past participles). This construction also suggests that it may be (or have been) difficult to produce a certain reaction on the part of the agent:
We'll get a monument erected on this site. The professor got his students to write an essay.

> When one wishes to express a change in temperament or in general conditions, it is the construction "to make + adjectif" which is used:
That letter made her sad. He makes me furious! That new problem made negotiations really hard!