I believe that it is very instructive for a programmer to spend some time with studying the evolution of the many programming languages created by Wirth, from Algol W and PL/360 to Oberon.
Because all his languages are relatively simple it is feasible to understand why some features are included or not and why they are implemented in a certain way and not in another.
While all his languages are interesting, they also have various shortcomings that make their use difficult in many more complex applications.
The main importance of the languages designed by Wirth is not in what they have been used directly to do, but in their great influence over many other more widely used programming languages.
Frequently, the innovations made popular by Wirth languages had already been introduced much earlier in other programming languages, but nobody was aware of that until Wirth made them well known.
For example, after Hoare introduced the "case" keyword, but with a syntax that was only a minimal improvement over the Algol "switch", Wirth introduced in Pascal (1970) the modern form of the "case" structure, with labeled alternatives (instead of using their ordinal position).
After that, practically all languages have included some variant of the labeled "case" (even when the older "switch" keyword was retained, like in C).
Nevertheless, it appears that neither Hoare nor Wirth nor anyone else was aware that McCarthy had introduced in LISP already at the end of 1958 the special form "select", with a syntax that was practically identical to the Pascal labeled "case", except that the LISP "select" had much fewer restrictions than the Pascal "case", because the labels could be not only constants but also expressions and the "select" could also be used as an expression, not only as a statement, like in Pascal.
There are also other examples like that, e.g. the modules of Modula have been much better known and influential than the modules of XEROX Mesa, which inspired Modula, and so on.
In any case the influence of Wirth over programming languages has been huge, even if many of the ideas propagated by him were not necessarily encountered for the first time in his work.
Because all his languages are relatively simple it is feasible to understand why some features are included or not and why they are implemented in a certain way and not in another.
While all his languages are interesting, they also have various shortcomings that make their use difficult in many more complex applications.
The main importance of the languages designed by Wirth is not in what they have been used directly to do, but in their great influence over many other more widely used programming languages.
Frequently, the innovations made popular by Wirth languages had already been introduced much earlier in other programming languages, but nobody was aware of that until Wirth made them well known.
For example, after Hoare introduced the "case" keyword, but with a syntax that was only a minimal improvement over the Algol "switch", Wirth introduced in Pascal (1970) the modern form of the "case" structure, with labeled alternatives (instead of using their ordinal position).
After that, practically all languages have included some variant of the labeled "case" (even when the older "switch" keyword was retained, like in C).
Nevertheless, it appears that neither Hoare nor Wirth nor anyone else was aware that McCarthy had introduced in LISP already at the end of 1958 the special form "select", with a syntax that was practically identical to the Pascal labeled "case", except that the LISP "select" had much fewer restrictions than the Pascal "case", because the labels could be not only constants but also expressions and the "select" could also be used as an expression, not only as a statement, like in Pascal.
There are also other examples like that, e.g. the modules of Modula have been much better known and influential than the modules of XEROX Mesa, which inspired Modula, and so on.
In any case the influence of Wirth over programming languages has been huge, even if many of the ideas propagated by him were not necessarily encountered for the first time in his work.