evaluator: add user-defined functions

src/Phsyche.package/PhsycheTest.class/instance/testLambdaProcedureExecution.st

@@ -0,0 +1,3 @@
+as yet unclassified
+testLambdaProcedureExecution
+	self assert: (ph parseAndEval: '((lambda (x) (* x x)) 3)') equals: 9.

src/Phsyche.package/PhsycheTest.class/instance/testProcedureDefinition.st

@@ -0,0 +1,7 @@
+as yet unclassified
+testProcedureDefinition
+	| proc |
+	ph parseAndEval: '(define squared (lambda (x) (* x x)))'.
+	proc := ph parseAndEval: #squared.
+	self assert: proc params equals: #(#x).
+	self assert: proc body equals: #(#* #x #x)

src/Phsyche.package/PhsycheTest.class/instance/testProcedureExecution.st

@@ -0,0 +1,4 @@
+as yet unclassified
+testProcedureExecution
+	ph parseAndEval: '(define squared (lambda (x) (* x x)))'.
+	self assert: (ph parseAndEval: '(squared 3)') equals: 9