Phrases become idioms in situation of poly-semantic coding of the words. This way is difficult to memorize. You should keep in mind each meaning. 100 accidental idioms -- 100 hard probes to memorize. More effective approach is to use proto-semantic features of tp. This way allows to build a sense that you want, when you need, and to extract a sense from phrases that you never used. The proto-semantics allows translate automatically, using only one linguistic formula. For example:combinations become idioms and what idioms they become is largely accidental from an external view. 'tomo awa' might have come to mean "hotel" but it didn't. Similarly, 'noka' could mean "walk", but we have settled on 'tawa noka' instead (this one subject to change, no doubt).
-- fish ("kala") has a mission "to swim" (actively)
-- liquid ("telo") has a mission "to flow" (passively)
If you go by the way of proto-semantics, you will never use the word "telo" for "swimming"-idioms.
-- direction ("tawa") has a mission "to direct" (passively -- to keep a direction)
-- head ("lawa") has a mission "to redirect" (actively -- to change a direction)
So, "tomo tawa" (hotel) and "tomo lawa" (headquarter) are strongly mutual related.
-- winter ("tenpo lete") -- season for cold
-- coat ("len lete") -- clothes for cold
These examples apply only one linguistic formula "thing_1 for thing_2".
Agree. The poly-semantic approach is the past of tp, the proto-semantics opens a "pona" future for tp.Evolution is slow but works pretty well.