After the freewheeling fifties, programming languages entered a more bohemian time, with many languages appearing, and those 1950s languages evolving, as new programming ideologies evolved. First out of the gate was ALGOL 60 which evolved from the fledgling Algol 58. It was common practice to “re-design” a language quite considerably, rather than make tweaks to an existing language. As such languages such as Algol 58 often fell out of favour as people adopted newer versions of a language. Algol was to spawn what would eventually become quite an issue in the computing community: augmentations, extensions, and derivations, leading to numerous dialects of a language. ALGOL 68 appeared just before its contemporaries C and Pascal, however due to inherent complexities, never really hit it off. (ALGOL 68 was used by European defense agencies, however the US decided to hedge its bets with Ada.) There was some controversy over the design of a successor to Algol 60, with Wirth and Hoare going on to develop their own successor, Algol-W. Algol 68 was a major revision to Algol 60, whereas Algol-W included more subtle changes. The 1960’s also saw a number of updates to both Fortran and Cobol.
Languages had also begun to diversify into differing realms. In 1964, Kenneth E. Iverson introduced APL, (A Programming Language) a concise symbol-based language adept at dealing with arrays. Early versions of the language contained no control structures, and whilst Cobol may have strayed too far into “English-language” syntax, APL may have gone too far with its mathematical syntax. APL was popular with those doing computer graphics, but its use declined in the 1980s, due in part to the advent of languages such as MATLAB and GNU Octave. The 1960s also saw the second generation of programming languages evolve, those influenced by the likes of Fortran or Algol. In 1964 PL/I (Programming Language One) made its appearance, supposedly for use in data processing, numerical computation, scientific computing, and systems programming. However it was a more complex language than either Fortran or Cobol, from which it had evolved, and was not extremely successful. Algol also influenced the design of Simula, the first OO language which appeared in 1967. In an educational context, Logo appeared in 1967, famous for its use of “turtle graphics”, influenced by Lisp.
P.S. If you want to have some fun with a Logo interpreter, check this out.