[lispm]

CMUCL was from the start very significant.

DEC Common Lisp was based on CMUCL. LispWorks was based on CMUCL. Scieneer Common Lisp is also based on CMUCL.

SBCL is a fork of CMUCL. SBCL is very popular in the 'free software' Lisp community - it's just a repackaged CMUCL.

Lot's of other Lisp implementations took and still are taking code from CMUCL, since it is 'Public Domain'. Free software.

Btw., CMUCL still has monthly releases.

AKCL spawned several implementations. Including GNU Common Lisp (GCL), which was widely used for some time - in combination with GCC.

GCL has been long used to run Maxima, the free version of Macsyma.

AKCL/GCL is nowadays ECL. Another fork. Which is maintained until today. Again ECL is possible because GCL was Free Software.

[JabavuAdams]

The paradox of choice.

One implementation that's good for 80% of users will gain more traction than 10 implementations where each user has to figure out which one to use.

Lisp attracts maximizers, while satisficers are more successful at delivering software to real people.