[mepian]

A compiler by itself is surprisingly easy, especially if you read Abdulaziz Ghuloum's or Jeremy Siek's tutorials. Making it competitive with state-of-the-art compilers like Clang or HotSpot is difficult, but this is true for every kind of software.

[shepherdjerred]

A compiler for a toy language is easy. 99% of professional programmers probably could not implement a compiler for C.

[account42]

A compiler for what? Some languages are easier than others.