The short answer is, yes, "The Matchmaker" is the play that was adapted into the musical "Hello, Dolly".
The longer and more pedantic answer is that "The Matchmaker" is the proximate source material for "Hello, Dolly", but was itself adapted from a play from a few decades earlier called "The Merchant of Yonkers", which was based on a 19th-century Austrian play called "Einen Jux will er sich machen", which was based on an earlier English play called "A Day Well Spent", which was, as far as we know, the original source material.
I happen to have a book of Thornton Wilder plays on my to-read shelf, so after I'd done my first read-through of the script for "Hello Dolly" I decided to read "The Matchmaker" as well to see the differences. I'm not sure if it helped as far as informing my work on "Hello Dolly"; my character is changed enough between versions that I'm not sure any insights carry over.
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The longer and more pedantic answer is that "The Matchmaker" is the proximate source material for "Hello, Dolly", but was itself adapted from a play from a few decades earlier called "The Merchant of Yonkers", which was based on a 19th-century Austrian play called "Einen Jux will er sich machen", which was based on an earlier English play called "A Day Well Spent", which was, as far as we know, the original source material.
I happen to have a book of Thornton Wilder plays on my to-read shelf, so after I'd done my first read-through of the script for "Hello Dolly" I decided to read "The Matchmaker" as well to see the differences. I'm not sure if it helped as far as informing my work on "Hello Dolly"; my character is changed enough between versions that I'm not sure any insights carry over.